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 Vice President Joe Biden has been hunkered down with advisers in his Delaware hometown, preparing to mount an energetic attack at Thursday night's debate. Mr Biden likely will home in on Mitt Romney's comments about the 47% of Americans he said pay no income taxes, believe they are victims and are dependent on the government. 
 
 In a Florida hotel, meanwhile, Republican vice-presidential nominee Paul Ryan and his advisers have been girding for precisely such an attack, and refining his argument that the country can't afford four more years of President Barack Obama's presidency. 
 
 The single vice-presidential debate has taken on ... ||||| DANVILLE, Ky. — And now for the undercard. 
 
 Paul Ryan will look to win for the Republican ticket tonight when he takes the debate stage at Centre College here against Joe Biden in the first national face-off in which he’s participated. 
 
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 Biden — for whom expectations have been lowered over the constant refrain of “What about your gaffes?” — will try his best to triumph, providing Democrats with a strong night to change the momentum of a race that has shifted slightly toward Mitt Romney. 
 
 (Also on POLITICO: Full coverage of the 2012 vice presidential debate) 
 
 The best case scenario for each? A clear win. The worst case scenario for each? A clear loss. The murkiest scenario for each? A debate that gets fought to a draw, which the press will interpret in different ways but which also likely won’t stop the GOP ticket’s momentum. 
 
 And of course, the debate’s subtext: Ryan and Biden are widely believed to be considering their own campaigns in 2016 (Ryan only if Romney loses). 
 
 (PHOTOS: Scenes from the VP debate) 
 
 Below, POLITICO’s five things to watch: 
 
 1. Can Biden draw blood? 
 
 Earlier this week, the congenitally quotable South Carolina Democratic Party Chairman Dick Harpootlian predicted that Biden would take “the old meat-ax” to Ryan — a beating so one-sided that “the humane society” would have to be called in. 
 
 It’s a hope shared by many Democrats — including President Barack Obama himself, who is publicly contrite over his passivity at last week’s Denver debate — flabbergasted by the prospect of the president standing by while Romney got away, in their minds, with 90 minutes of lies, mischaracterizations and manufactured positions contrary to his own history. 
 
 (See also: Complete coverage of 2012 presidential debates) 
 
 Biden, one of his staffers told POLITICO, is “eager to draw the contrast — and very capable of doing so.” 
 
 But will it work? 
 
 Ryan’s perceived weakness — his wonkery and penchant for speaking in numbers — may actually prove to be the congressman’s greatest asset, a rope-a-dope tactic that will take voters into the policy weeds and blunt Biden’s attacks on tax policy, spending and foreign affairs. Obama was momentarily captivated by the Wisconsin congressman earlier in his term, telling aides that he was one of the few members of the GOP congressional crew he actually respected on an intellectual level. 
 
 But the vice president has his own arguments to make. Biden is likely to hammer away at the Medicare cuts Democrats claim are at the core of the Ryan budget passed by the GOP-controlled House, with polls showing older voters in key battlegrounds like Florida and Ohio deeply skeptical of the Republican approach. Biden, aides say, is also likely to emphasize Romney’s on-again, off-again support for Ryan’s plan — in an attempt to wedge the two apart. ||||| Thank goodness the Daily Caller has got some game for exposing conflicts of interest and really important stuff that other news sites are missing. The website known for saying that it has unearthed scandals said Wednesday it had unearthed the shocking news that the moderator of Thursday’s vice presidential debate once had someone named Barry Obama as a guest at the first of her three weddings. 
 
 Now most of us in the political press have become far too complacent to backtrack even one wedding into the past of the debate moderators. So, of course, we would miss the glaring conflicts that can be exposed by journalists who dig really, really deep. 
 
 The Daily Caller has revealed that debate moderator Martha Raddatz of ABC News had the self-same Obama at her wedding 21 years ago. And now we are less than 24 hours away from this obvious toady throwing out questions to the two men – Vice President Joe Biden and Rep. Paul Ryan — who would like to be a heartbeat away from the Oval Office that Obama now occupies. 
 
 PHOTOS: Memorable presidential debate moments 
 
 The Daily Caller article clearly suggests that Raddatz’s early 1990s interlude with the man later to be known as Barack should disqualify her from overseeing the contest between Biden and Ryan. 
 
 Skeptics of the right-wing Daily Caller expose might note that Obama was only one of a bunch of Harvard Law School types at the wedding. And that his main connection to the event appeared to be as a friend of the groom, law school classmate Julius Genachowski. And that Raddatz and Genachowski divorced years ago. 
 
 Those niceties would only be pointed out, though, by apologists for the hopelessly biased left-wing press corps. 
 
 Raddatz might have moved on to a couple more marriages and an award-winning career as a White House and then foreign correspondent. But Peabody, Emmy and other awards can’t cover up the hard fact: She partied with the future president. 
 
 You can almost feel the Daily Caller follow-ups: First, eyewitness accounts of Obama catching the Raddatz garter. Then the tell-all video: Raddatz and Obama, mere feet apart on the dance floor, boogieing as only undisciplined left-wingers can. 
 
 PHOTOS: President Obama’s past 
 
 Such associations certainly preclude one person from ever writing and reporting fairly about another. Surely, Raddatz should be forced from her position as senior foreign affairs correspondent for ABC. She may have made dozens of courageous trips to Iraq and Afghanistan. But how can she be fair about Obama’s role in those overseas wars after that glass of Mumm’s back in '91? 
 
 Innocent Paul Ryan has no idea he is about to be blindsided by someone who once may or may not have danced the lambada with President Obama. A naïve Ryan spokesman, asked about the nefarious Raddatz, avowed to having “no concerns.” 
 
 INTERACTIVE: Battleground states map 
 
 Follow Politics Now on Twitter and Facebook 
 
 james.rainey@latimes.com 
 
 twitter.com/@latimesrainey 
 
 MORE COMMENTARY FROM JAMES RAINEY 
 
 Debate moderator "Silent Jim Lehrer" gets one last turn 
 
 Presidential debate: Round One goes to Romney, by many measures 
 
 Romney on a roll? Remember John Kerry, in debate, beat George W. Bush 
 
 ||||| CNN will offer unrestricted access to Thursday's vice presidential debate coverage starting at 7 p.m. ET on CNN TV, CNN.com and via CNN's apps for iPhone, iPad and Android. Web users can become video editors with a new clip-and-share feature that allows them to share favorite debate moments on Facebook and Twitter. Follow CNN's live blog and visit the CNN debates page for instant updates and comprehensive coverage. 
 
 Danville, Kentucky (CNN) -- Vice President Joe Biden and Rep. Paul Ryan, GOP presidential candidate Mitt Romney's running mate, will share the stage in Danville, Kentucky, in their only debate. Biden and Ryan's debate follows the top of the tickets' first of three debates last week, in which Obama turned in a lackluster performance, upstaged by an aggressive and vibrant Romney. 
 
 Here are five things to watch for on Thursday night: 
 
 1. Will Biden go where Obama didn't? 
 
 Biden is not shy on the campaign trail; the day after last week's first presidential debate, the vice president attacked Republican nominee Mitt Romney in a way that many Democrats had wished President Barack Obama would have done the night before. 
 
 King: VP debate no game-changer, but could shift momentum 
 
 How aggressive will Biden be in going after the man at the top of the GOP ticket rather than the man he'll share the debate stage with? Will Biden highlight the "47%" controversy, Bain Capital and Romney's tax returns? 
 
 "The vice president likes laying out the contrast between the Romney-Ryan extreme agenda and the plans he and the president have to move this country forward and we fully expect that to continue Thursday night," an Obama campaign official told CNN. 
 
 With the polls tightening both nationally and in key battleground states after last week's debate, the stakes for the showdown between the running mates have increased. 
 
 7 questions you would ask at the VP debate 
 
 "Biden needs to play offense, not defense," said Democratic strategist and CNN contributor Paul Begala, who is a senior adviser for a pro-Obama super PAC. "Attack the Romney-Ryan plan to cut taxes for the rich and raise them on the middle class. Dissect the Romney-Ryan plan to end Medicare as we know it. Point out that if Romney had been president, Osama bin Laden would be alive and GM would be dead. And be prepared to body-slam Ryan when -- not if -- he fibs." 
 
 2. The wonk trap 
 
 Paul Ryan likes to call himself "a numbers guy." 
 
 Indeed, wonky budget talk is Ryan's calling card. It's the primary reason he has captured the hearts of conservative elites in Washington, who see him as the second coming of Jack Kemp. 
 
 Ryan's debate prep as meticulous as he is 
 
 But fiscal wonkery was quicksand for Obama during last week's debate. His dreary reliance on budget math over pointed political arguments contrasted sharply with Mitt Romney, who presented his ideas with vigor and clarity, despite obvious questions about the factual underpinnings of his ideas. 
 
 Can Ryan avoid getting bogged down in the arithmetic that so thrills him? An adviser to the GOP vice presidential nominee told The National Review's Robert Costa this week that Ryan "may be over-preparing" for his showdown with Biden. 
 
 By some accounts, Ryan has bristled at platitude-driven demands of the campaign trail. He'd rather be talking substance, on the road with a PowerPoint presentation about Medicare costs. 
 
 The challenge for Ryan on Thursday, though, is to present the Romney vision to millions of voters without sounding too much like the Beltway think tank staffer he once was. 
 
 He's done a solid job of that since Romney put him on the GOP ticket in August. Now, on the biggest stage of his career, he has to abandon some of the Capitol Hill tendencies that made him a star in the first place. 
 
 Paul Ryan hasn't called Palin for advice 
 
 3. Will Biden put Social Security in play? 
 
 In the House, Paul Ryan has backed moving Social Security funds to private investment accounts as a way to make the popular entitlement program more solvent. 
 
 Ryan's past proposals would seem to tee up what's usually a winning political argument for Democrats: that the Republican ticket wants to gut Social Security to help their old pals on Wall Street. 
 
 But to the bewilderment of Democratic strategists, Obama appeared to take the issue off the table in the first debate. 
 
 "I suspect that on Social Security, we've got a somewhat similar position," Obama said. "Social Security is structurally sound. It's going to have to be tweaked the way it was by Ronald Reagan and Democratic Speaker Tip O'Neill. But it is, the basic structure is sound." 
 
 CNN Money: Social Security, Where Obama and Romney stand 
 
 The Obama campaign scrambled to clarify last week that yes, in fact, the two candidates have fundamentally different views on Social Security. 
 
 "The choice is clear: President Obama will never privatize Social Security or undermine retirement security for middle-class Americans," read a post on the Obama campaign website that went up after the debate. "The same cannot be said for Romney." 
 
 Will Biden try to score fresh points by raising the issue of Social Security privatization against Ryan? Or did the president already holster one of his party's most effective political attacks? 
 
 4. The age gap 
 
 "I am not going to exploit for political purposes my opponent's youth and inexperience." 
 
 So went Ronald Reagan's famous line in one of his 1984 debates against Democratic challenger Walter Mondale. 
 
 Will Biden have a similar quip ready on Thursday? 
 
 OK, Biden is not nearly as old as Reagan, who was 73 at the time of his re-election. But at 69, he has almost three decades on Ryan, his 42-year-old debate opponent. 
 
 How Ryan sharpens debate skills 
 
 Biden is also known for his exuberance and devilish charm, so perhaps the age gap won't be as apparent as it was in 2008, when 47-year-old Barack Obama shared a stage with 72-year-old John McCain. Or as it was in 1988, when 67-year-old Lloyd Bentsen debated his boyish vice presidential foe Dan Quayle. 
 
 Stylistically, their birthdays might not matter much. But the age difference neatly crystallizes the arguments being presented by both campaigns. 
 
 Will voters choose experience and decide to move forward on the path we're on? Or will they look to a pair of fresh-faced outsiders who offer a new direction? 
 
 5. Ryan's role as commander in chief 
 
 Just as Mitt Romney needed to prove last week that he's acceptable to Americans to serve as president, Ryan needs to convey that he's ready to fill in as president in case something happens to Romney. It's one of the top tasks for the challenger's running mate in a vice presidential debate. 
 
 We'll be keeping a close watch on Ryan to see if he touts his ability to step in, if needed, to the leading role. 
 
 The Romney campaign is confident that the congressman from Wisconsin will pass the test, thanks to Ryan's position as House budget chairman and his mastery of complex fiscal issues. 
 
 "It will come down to his competency on the issues, his command of the issues," a Romney campaign official told CNN. 
 
 But Republican strategist and CNN contributor Alex Castellanos thinks that this time around, passing the competency test is not as important. 
 
 "There is very little pressure for either of these vice presidential candidates to prove they are ready to step into the office of president. Both their bosses are relatively young and in great health," Castellanos said. 
 
 Opinion: Biden must deliver for Team Obama 
 
 What questions would you ask the VP candidates? Share with us on CNN iReport
– There's a whiff of desperation in the air over tonight's vice presidential debate—and a hint of controversy, too. The desperation, of course, comes from the blue team, which is desperate to halt the momentum Mitt Romney gained in the first debate, and expects Joe Biden to be especially aggressive in attacking Paul Ryan. The controversy? A conservative site has dug up evidence that President Obama may have attended moderator Martha Raddatz's wedding. Here's what you need to know: The Daily Caller has found that Obama had attended the first of Raddatz's three weddings, back in 1991—he was a Harvard Law classmate of groom Julius Genachowski, who he later named to head the FCC. But the LA Times is not impressed, writing snarkily that "most of us in the political press have become far too complacent to backtrack even one wedding into the past of the debate moderators." Everyone is expecting Biden to come out swinging. One Biden staffer tells Politico that the VP is "eager to draw the contrast—and very capable of doing so." Ryan himself told a radio station yesterday that he expects Biden to come at him like a "cannonball," according to USA Today. Expect Biden to go on the attack when it comes to Ryan's Medicare plan in particular. CNN also wonders if Biden will bring up Social Security. Ryan has advocated moving the funds into private investment accounts, an idea Democrats usually attack profitably—but Obama appeared to take it off the table in the first debate, saying he suspected he and Romney had "a somewhat similar position." Ryan's team also expects Biden to bring up Romney's 47% gaffe, and they tell the Wall Street Journal that they've specifically been prepping a response to it. On Ryan's end, everyone's wondering just how wonkish he'll be. CNN worries he'll get "bogged down in arithmetic," but Politico suspects it could be his "greatest asset, a rope-a-dope tactic that will take voters into the policy weeds." Of course, all this sound and fury might not signify much. "By tradition, the vice presidential debates have been like the vice presidency itself: well-publicized but largely inconsequential," quips the Washington Post, noting that Gallup studies found they'd never had a significant impact on the race.