What To Watch For At Democrats' First Debate 
 
 A bruised Hillary Clinton will have much to prove as she takes the debate stage Tuesday evening alongside four of her Democratic presidential challengers. The former secretary of state has been damaged by lingering questions about her private email server and doubts about her trustworthiness. 
 
 That has partly enabled Vermont independent Sen. Bernie Sanders to ride a wave of progressive support to a lead over her in New Hampshire and an impressive $25 million fundraising haul last quarter. 
 
 Sanders, too, will need to impress in his most high-profile appearance so far. This will be the first chance for many voters to see him on stage, and they'll be watching to see if he's someone they want to be president. 
 
 "It's certainly not going to be as entertaining as some of the previous Republican debates, but it will be important, especially for Hillary Clinton and Bernie Sanders, to finally show the broader public what exactly they're made of," said Jim Manley, a longtime Democratic strategist and former top Senate aide. 
 
 Of course, there's also the elephant — or, rather, the donkey — in the room: Vice President Joe Biden. He's not yet announced his intentions, as he continues a public flirtation with a bid. CNN has left open the possibility of allowing Biden on stage, even if he were to decide as late as Tuesday. He has given no indication that he will do so. 
 
 But perhaps the most important thing for Democrats is that it's finally their turn in the political spotlight. After two rollicking GOP debates and a cycle that's largely been dominated by the outsiders in the Republican field, party loyalists have worried they are being overshadowed. 
 
 "This is the first real opportunity for a Democratic message to break through," said Mo Elleithee, a former Democratic National Committee communications director who now directs the Georgetown Institute of Politics and Public Service. "The numbers game is working against us right now, and the Republican message is penetrating far more than the Democratic message." 
 
 Here's what to watch for from each candidate in the first Democratic debate. CNN's coverage begins at 8:30 p.m. ET, while the debate is expected to start at 9 p.m. ET Tuesday on CNN. 
 
 Hillary Clinton 
 
 Enlarge this image toggle caption Matt Rourke/AP Matt Rourke/AP 
 
 Need: Appear likable and straightforward, especially when talking about those emails and recent policy positions 
 
 Avoid: Complicated explanations and defensiveness 
 
 She will be center stage and the center of attention. She's the most experienced campaign debater on stage — there were 25 primary debates in 2008 — and that will be an asset. But Clinton still has some of the same struggles she had eight years ago — trying to appear likable and not scripted to a public very skeptical of traditional politicians. 
 
 "In Hillary's case, she has to be more likable and come across as genuine and down to earth," said Dan Payne, a Democratic strategist and debate coach. "She is those things, from what people say who know her well. She can talk to day-to-day people about their lives and share experiences, but somehow it doesn't come across when she's on camera. She gets stiff and stern, and not likable." 
 
 She wasn't that way during her cameo on Saturday Night Live last week, Payne noted, and that should be an instance her team should draw from. 
 
 "She was self-aware," he added. "She was poking fun at herself and doing it with a laugh. If she can do that in the debate occasionally, it can help." 
 
 One of the first questions directed to her will likely be about her email server. She has yet to put to rest questions about why she had the private server and whether it was a security threat. Last month she finally apologized for the decision, but it may have been too little too late. 
 
 In an interview on 60 Minutes on Sunday, President Obama said the server was not a national-security threat. But he did not forcefully defend Clinton, instead directing questions back to her. 
 
 "I would hope that, if pressed, she would again apologize for allowing this to be an issue in the first place," said Manley, who is a Clinton supporter. 
 
 It's no mistake that in the run-up to the debate, Clinton came out against both the Keystone XL Pipeline and Obama's Trans-Pacific Partnership, something she once called the "gold standard" of trade agreements. Clinton was trying to clean up messy policy positions ahead of the debate. 
 
 But Clinton will still likely have to answer whether the moves were politically calculated. Sanders and former Maryland Gov. Martin O'Malley have been against both for some time; expect them to point out the disparity. 
 
 Bernie Sanders 
 
 Enlarge this image toggle caption Rick Scuteri/AP Rick Scuteri/AP 
 
 Need: Convince a national audience he's presidential material and that he can branch out beyond his core economic message 
 
 Avoid: Lapsing into testiness 
 
 While Sanders may not have had much campaign debating experience — he has faced mostly safe elections in Vermont — he does have more than two decades of congressional experience to draw from. He brings skills debating on the House and Senate floor and in committees to Tuesday's event. 
 
 His challenge will be translating the considerable enthusiasm he's been generating on the campaign trail to the debate stage. Filling arenas is quite impressive, but facing questions from moderators and elbows from his rivals is another thing entirely. 
 
 "He can give a line or two or three and get a roar from the crowd," Payne said, "but you have much longer in a TV debate — you have to sustain your argument for 45 seconds to a minute." 
 
 Don't expect Sanders to go for the jugular against his chief rival, though. As much as the moderators might try to goad him into it, the Vermont senator has largely avoided direct attacks on Clinton, and his team has telegraphed to expect the same on Tuesday. Instead of focusing on lobbing hits, Politico reported, his somewhat limited debate prep has instead been policy-heavy. 
 
 Ultimately, Democrats say, they don't anticipate fireworks between the two top candidates. 
 
 "I suspect that neither one is really going to go after the other," predicted Elleithee, who worked on Clinton's 2008 campaign. "They may disagree, and they will point out where they disagree. That's normal, and that's fine. But I don't think you'll see either one come in and try to tear the other one down. That would be a bad strategy." 
 
 But Sanders will have to keep his cool throughout the debate, too. He's been testy with reporters when pressed in the past, and that type of reaction might not play well in front of a national TV audience. 
 
 "In Bernie's case, he has to be in control and not appear unpleasant — be a man who you could conceivably believe is president," said Payne, the debate coach. "If you're angry, it may come across as extremely harsh." 
 
 Martin O'Malley 
 
 Enlarge this image toggle caption Jim Mone/AP Jim Mone/AP 
 
 Need: Show he belongs in consideration as a top-tier candidate 
 
 Avoid: Debating about debates and getting on a high horse 
 
 Former Maryland Gov. Martin O'Malley has struggled to catch fire, but has also proven to be the most dogged Clinton attacker of the bunch — another element Clinton will have to manage. 
 
 Ultimately, O'Malley may have the most to gain and the most to lose during Tuesday's debate. Once seen as a rising star in the Democratic Party, he was supposed to have been the top alternative to Clinton. Instead, that distinction has gone to Sanders (or possibly even Biden, if he does indeed run). 
 
 Now, O'Malley needs to give a rationale for his candidacy and prove he can be an able sparring partner with both Clinton and Sanders. O'Malley has vigorously pushed for more debates instead of the scheduled six face-offs, and he needs to show why that's a good idea for him. 
 
 "This could be his Scott Walker moment," Elleithee said, comparing O'Malley to the Wisconsin governor whose presidential campaign was doomed after a dismal performance in the second GOP debate. 
 
 "O'Malley can either break through and show he deserves to be considered as a top-tier candidate," he continued, "or if he doesn't break through, his advisers are going to have to circle up, re-calibrate, and figure out what they're going to say to donors. The rationale for his candidacy is not very evident." 
 
 That doesn't mean O'Malley should come in being a bomb-thrower, which could backfire on stage. Instead, he needs to draw well-reasoned contrasts with his opponents. 
 
 One top issue where he could do that is on gun control, which is back in the news after yet another mass shooting last week. O'Malley has, by far, the most progressive and far-reaching plan of any Democratic candidate. He also stands in contrast especially with Sanders, who has had a mixed record on the issue. 
 
 Jim Webb and Lincoln Chafee 
 
 Need: A breakout moment to show they're serious candidates 
 
 Avoid: Getting left out of the conversation 
 
 The other two candidates on stage — former Virginia Sen. Jim Webb and former Rhode Island Gov. Lincoln Chafee — have been almost entirely absent from the campaign trail and will simply need to explain why they're in the race. Both need to introduce themselves to voters, as expectations are already very low. 
 
 Webb, the only veteran on the stage, could bring a valuable voice in terms of foreign policy and national security. 
 
 "He needs to tell his story," Payne said. "He was a star in the making eight years ago, but once he left the Senate, his star has all but extinguished." 
 
 Chafee, a former GOP senator turned independent turned Democrat, could still have to explain his liberal bona fides and defend a controversial tenure as Rhode Island governor. Expect him to needle Clinton on her vote for the Iraq War — and to point out that even as a Republican, he opposed it from the start. 
 
 Both Webb and Chafee need a breakthrough moment. ||||| Watch the first Democratic presidential debate Tuesday at 8:30 p.m. ET live on CNN and CNNgo ; join the conversation at #DemDebate 
 
 (CNN) Five Democratic presidential candidates are about to try their luck at the first Democratic debate of the 2016 election in Las Vegas on Tuesday night. 
 
 But the spotlight is largely on two: former Secretary of State Hillary Clinton and Vermont Sen. Bernie Sanders. 
 
 The former secretary of state needs to remind viewers of the debate sponsored by CNN and Facebook about why she began the year as the overwhelming front-runner and is best able to take the torch from President Barack Obama. 
 
 Sanders has the opportunity to prove to millions of voters why a 74-year-old self-described democratic socialist can take on both Clinton and Republicans. 
 
 There's also a lot at stake for the three lesser known underdogs, particularly former Maryland Gov. Martin O'Malley, whose stalled campaigns could benefit from an "all in" performance Tuesday. 
 
 Here are CNN's six things to watch in Tuesday night's debate: 
 
 Can Clinton flip-flop gracefully? 
 
 Hillary Clinton will have to answer for the original sin of politics: flip-flopping. 
 
 JUST WATCHED Hillary Clinton's past debate moments Replay More Videos ... MUST WATCH Hillary Clinton's past debate moments 03:32 
 
 Clinton came out against the Trans Pacific Partnership last week, when as secretary of state she heralded the agreement as the "gold standard" of trade deals. Her critics quickly accused her of shifting positions for the sake of political expediency in both appealing to liberals and creating distance between her and Barack Obama. 
 
 "Wow, that's a reversal," O'Malley, a TPP opponent, said last week. "I can tell you that I didn't have one opinion eight months ago and switch that opinion on the eve of debates." 
 
 Clinton has also been accused of doing a course reversal on issues important to the Democratic base, like same-sex marriage and whether she supports allowing undocumented people to obtain driver's licenses. She also only recently opposed the Keystone XL pipeline, after months of dodging the question. 
 
 "The greatest opportunity for these other candidates is going to be to go after her on shifting positions, mostly recently on the TPP trade deal," Dan Pfeiffer, a former senior adviser to Obama, said on CNN Monday. 
 
 The emails: Will anyone go there? 
 
 Clinton has battled, unsuccessfully for months, to overcome the political storm over her private email server. 
 
 The attacks have been led by Republicans while Democrats have mostly averted their gaze, hoping it would go away. 
 
 It's a tricky issue for a rival candidate to bring up -- they could risk harming their own support among Democrats by raising the divisive issue. But it's still possible that Clinton's rivals -- perhaps Webb or O'Malley -- will gingerly point to the issue on Tuesday as a way of suggesting that she abhors transparency and scrutiny. 
 
 "She needs to answer the email questions with transparency and openly," Patti Solis Doyle, Clinton's 2008 campaign manager, said on CNN Monday. She added that Clinton's biggest challenge is to avoid getting "riled up" if put on the defensive. 
 
 Clinton's campaign has seized on comments by GOP House Majority Leader Kevin McCarthy that the congressional Benghazi committee was created to hurt her politically, as well as criticisms of the panel by a conservative former staffer. 
 
 Donald Trump: Democrats' favorite punching bag? 
 
 If Democrats don't attack Clinton, who will they hit? Republicans. Especially Trump, the GOP front-runner whose unorthodox campaign has dominated the 2016 narrative so far. 
 
 Look for the five Democrats on stage to go after Republicans from the start. The wealthy New York real estate developer presents an alluring target, and the more they can tie Trump to the overall Republican Party, the better. 
 
 The Democratic Party has used some of Trump's unfiltered remarks on everything from immigration to women to paint the GOP with a broad brush and label the party as exclusive and intolerant. 
 
 Feel the Bern 
 
 By now, Bernie Sanders is used to being the star at the center of the stage. 
 
 He's drawing tens of thousands of supporters to campaign rallies, and he's become a liberal sensation, inspiring the popular slogan "Feel the Bern" among progressive Democrats. He's also giving Clinton a run for her money in early states like Iowa and New Hampshire. 
 
 Still, the pressure Tuesday night will be like none the Vermont senator has faced so far in the cycle. 
 
 JUST WATCHED How a Bernie Sanders event differs from a Hillary Clinton one Replay More Videos ... MUST WATCH How a Bernie Sanders event differs from a Hillary Clinton one 02:25 
 
 Sanders has decades of experience in public office, but in some ways, he seems like a stylistic misfit for the presidential debate stage based on the campaign he has run thus far. He tends to give long and at times rambling speeches, he has repeatedly said he has no interest in attacking his fellow Democratic rivals, and his aides say he's barely engaged in traditional debate prep in the days leading up to Tuesday. 
 
 The added challenge for Sanders will be to win over viewers who are skeptical about whether the senator can rise to the occasion of being a national leader. 
 
 Which Clinton shows up? 
 
 Clinton has spent months on the defensive, due to the controversy over her private email server and surprised by the strong progressive surge that's powering Sanders to her left. 
 
 She's come across as not forthcoming in some interviews, reminding voters of the political obfuscation that at times clouded her husband Bill Clinton's administration in the 1990s. Clinton's poll numbers and approval ratings have dipped as a result. 
 
 But she's a known strong debater, and went toe to toe with Barack Obama again and again in 2008. A repeat of those assured, likable performances on Tuesday night could go a long way toward reminding 18 million Democrats why they voted for her in her first presidential primary campaign. 
 
 "Hillary Clinton is an excellent debater," said Pfeiffer. "She is excellent, crisp, knows the substance up and down, is very good in the back and forth." 
 
 For all her struggles in the race so far, she is still the overwhelming front-runner and faces by far the highest expectations. 
 
 Clinton also knows the dangerous potential of debates. Her halting answer about driving licenses for undocumented migrants in the 2008 season was the first crack in a front-running White House campaign that Obama eventually overhauled. 
 
 Is this Martin O'Malley's only chance? 
 
 O'Malley has spent months berating Democratic leaders for failing to schedule more debates, all as he has struggled to climb above single digits in the polls. 
 
 Once seen as a fresh and accomplished new Democratic voice, the former Maryland governor -- partly due to his failure to command much media coverage -- is badly in need of a fresh boost of energy. 
 
 He and his other underdog rivals, Jim Webb and Lincoln Chafee, will want to emulate Carly Fiorina. The former Hewlett-Packard CEO used fiery performances in the GOP debates to jump-start a stalled campaign and put herself into the top tier of GOP candidates. 
 
 O'Malley, 52, is also by far the youngest person on the stage. Sanders is 74, and was born months before America entered World War II. Most of the rest are baby boomers. Clinton is 67, Jim Webb is 69 and served in the Vietnam War, and Lincoln Chafee is 62. 
 
 Unlike the Republican primary, which features candidates spanning generations -- Marco Rubio and Bobby Jindal are just 44 -- the Democratic contest looks like it is for seniors only. The age gap could give O'Malley an edge. And he'll need any advantage he can get. 
 
 "The one person who has a great opportunity here is Martin O'Malley," former Mitt Romney adviser Kevin Madden said on CNN Monday. "When you're at 1%, and you're Martin O'Malley, that's very easy. He has nowhere to go but up." 
 
 Clarification: This story has been updated to better reflect Clinton's position on immigration policy. ||||| Vice President Joe Biden hasn't said if he'll run for president, but if he decides by Tuesday, he will have a spot on the debate stage. Video provided by Newsy Newslook 
 
 Hillary Clinton speaks at an awards gala sponsored by the Congressional Hispanic Caucus Institute on Oct. 8 (Photo: Teresa Kroeger, Getty Images) 
 
 The only participant at the first Democratic debate of the 2016 presidential campaign with nothing to prove is Sheryl Crow, the singer slated to open the evening by singing the National Anthem. 
 
 But for Hillary Clinton, Bernie Sanders, Martin O'Malley, Jim Webb and Lincoln Chafee, the stakes in Las Vegas Tuesday are going to be high. The two Republican debates held so far — boosting neurosurgeon Ben Carson and former CEO Carly Fiorina into top GOP ranks — have demonstrated the impact the nationally televised forums can have to shape and reshape voters' impressions. 
 
 Here's a quick look at what each of the Democratic candidates needs to do. The debate, sponsored by CNN and moderated by Anderson Cooper, starts at 8:30 PM ET. 
 
 'HELLO, I'M HILLARY' 
 
 Since Hillary Clinton formally announced her campaign in April, she's seen her poll standings fall and the controversy over her use of a private email server while secretary of State heat up. After a quarter-century in national politics, she no longer has a chance to make a first impression, but the debate does offer an opportunity for her to explain who she is and why she's running. 
 
 "Whatever her message has been, it's been drowned out by emails and servers and the opposition," Democratic strategist Joe Trippi, a veteran of past presidential campaigns, said in an interview. ""This is a real chance for her to lay it out." 
 
 What analysts don't expect her to do is attack challenger Bernie Sanders, whose supporters she will need if and when she wins the nomination. "Frankly, both Sanders and Clinton need to communicate warmth," says Democratic pollster Margie Omero. In contrast to the confrontational back-and-forth of the Republican debates, she says, "we may be able to determine the winner by looking at which candidate smiled the most." 
 
 That's not to say Clinton won't be attacked by others, on issues ranging from her 2002 vote in favor of the Iraq war to her reversal last week to oppose the Trans-Pacific Partnership. "She has to be prepared to answer the inevitable flip-flop question," says political scientist Dante Scala of the University of New Hampshire. 
 
 Strategists say Clinton, who has been on the defensive for months, needs to project an open manner. "This is really about her not having a shield up," Trippi says. 
 
 Sen. Bernie Sanders of Vermont at the University of Colorado in Boulder on Oct. 10 (Photo: David R. Jennings, AP) 
 
 A PLAUSIBLE PRESIDENT 
 
 Vermont Sen. Bernie Sanders arrives at the debate in a stronger position than even some of his top strategists initially thought possible. He has become a hero to progressive voters and the chief challenger to Clinton, and he is now drawing bigger crowds, more enthusiasm and nearly as much money as she is. 
 
 Expanding his appeal beyond his liberal base is his next task. "It's enough to get you 25%, 30% of the vote — and you're done," Trippi warns. "If you can't broaden to moderate blue-collar Democrats, Catholic Democrats, to African Americans and Hispanics, you can't win the nomination." 
 
 When the debate ends, success for Sanders would be "that Democratic primary voters find a Sanders presidency plausible," says Scala, co-author of The Four Faces of the Republican Party, being published by Palgrave Pivot next month. "It's one thing to be a prophet in the wilderness. It's another to be presidential. That's Sanders' challenge." 
 
 Sanders says his message espousing economic equity is one that resonates with many voters, including those who may not consider themselves particularly liberal. But the cost of his proposals are jaw-dropping. A Wall Street Journal analysis calculated it at $18 trillion in new government spending over the next decade. 
 
 "The big issue he'll need an answer for is on guns," Omero predicts. Sanders has opposed some proposals to limit access to guns, a record he argues reflects the sentiments of his constituents. The mostly rural Green Mountain State has one of the highest rates of gun ownership in the country. 
 
 Martin O'Malley addresses the New Hampshire Democratic Party State Convention on Sept. 19 (Photo: Scott Eisen, Getty Images) 
 
 I'M STANDING RIGHT HERE 
 
 If Sanders arrives at the debate in a stronger position than expected, Martin O'Malley arrives in a weaker one. The former two-term governor of Maryland has campaigned hard but still barely registers in national polls. The RealClearPolitics average of recent surveys puts his support at less than 1%. 
 
 "For the first time, O'Malley is finally going to have an audience," Trippi says. O'Malley has been more willing than Sanders to go after Clinton on the email controversy and on her changes in position in recent weeks to oppose the Keystone XL Pipeline and the Pacific trade deal. O'Malley needs a breakthrough moment or an exchange during the debate that convinces Democratic voters to consider his candidacy. 
 
 Jim Webb at the Iowa State Fair on Aug. 13 (Photo: Justin Sullivan, Getty Images) 
 
 REMEMBER IRAQ 
 
 Former Virginia senator Jim Webb has been running a low-profile, low-budget campaign. But his centrist views and his blunt manner gives him the potential to challenge the contenders seen as more likely Democratic nominees. He supports construction of the Keystone XL Pipeline, for instance, and argues that President Obama wasn't tough enough in the Iran negotiations. He also cites his opposition to the invasion of Iraq as a key selling point, which means he is likely to force Clinton to defend or at least discuss her 2002 vote to authorize the military action when she was a senator from New York. That was the main issue Barack Obama used in challenging Clinton in the 2008 primary campaign — which he won. 
 
 Lincoln Chafee at the New Hampshire Democratic convention on Sept. 19 (Photo: Jim Cole, AP) 
 
 RHODE ISLAND RESUME 
 
 Lincoln Chafee has the broadest political experience of anyone running for president in 2016. The Rhode Islander has served as a mayor, U.S. senator and governor, and he's run for office as a Republican, then an independent, and now as a Democrat. "He seems like a decent fellow," Trippi offers. That said, Chafee's resume hasn't made him a particularly serious contender. In the debate, he needs the same sort of breakthrough moment as O'Malley and Webb, but analysts say his reserved manner may make it harder for him. 
 
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– Hillary Clinton is now, officially, at long last, Ready for Hillary. She jumped back into presidential politics today as a top adviser announced her much-awaited second campaign for the White House. The adviser, John Podesta, told alumni of her first presidential campaign in an email: "It's official: Hillary's running for president." Clinton followed with a video released on YouTube that depicts people going through life challenges like moving, job-hunting, and starting a family, the New York Times reports. "I'm getting ready to do something too," Clinton says, appearing a minute-and-a-half in. "I'm running for president. ... Everyday Americans need a champion. And I want to be that champion." Clinton is expected to face pressure from progressives to adopt a more populist economic message focused on income inequality. The GOP, meanwhile, has already started attacking her, jumping on Clinton's use of a personal email account and server while secretary of state. Clinton is the first Democrat to get into the race and is not expected to be seriously challenged, the Times notes, but there are some lower-profile Democrats who may toss a hat in the ring, including former Maryland Gov. Martin O'Malley, former Virginia Sen. Jim Webb, and former Rhode Island Gov. Lincoln Chafee. If elected, Clinton would become the first woman to serve in the Oval Office. (Meanwhile, Kate McKinnon's version of Hillary Clinton made her announcement last night on Saturday Night Live.)