Photographer: SeongJoon Cho/Bloomberg 
 
 President Obama's high-stakes bid to complete one of the largest free trade pacts in U.S. history--over the objections of most Democrats--moved ahead Thursday when the Senate introduced bipartisan legislation that would give his administration vast new powers to close the deal. 
 
 The fast-track trade bill from Sens. Orrin G. Hatch (R-Utah) and Ron Wyden (D-Ore.) would allow the president to present a final agreement to Congress for an up-or-down vote without lawmakers being able to amend the terms. A similar bill, drafted by Rep. Paul Ryan (R-Wis.), is expected to be introduced in the House in the coming weeks. 
 
 Hatch, chairman of the Senate Finance Committee, said he would hold a markup and vote on the bill April 23. 
 
 [Obama’s proposal for more trade with Asia may not go over so well in his own party] 
 
 Obama administration officials have called fast-track authority crucial to wrapping up negotiations on the Trans-Pacific Partnership (TPP), a 12-nation trade and regulatory deal in the Asia Pacific that Obama has touted as a cornerstone of his second-term agenda. 
 
 "My top priority in any trade negotiation is expanding opportunity for hardworking Americans," Obama said in a statement Thursday. "It’s no secret that past trade deals haven’t always lived up to their promise, and that’s why I will only sign my name to an agreement that helps ordinary Americans get ahead. At the same time, at a moment when 95 percent of our potential customers live outside our borders, we must make sure that we, and not countries like China, are writing the rules for the global economy." 
 
 The president has said the deal would help ensure U.S. competitiveness in the face of a rising China. But getting it across the finish line on Capitol Hill will mark a major leadership test for Obama. The deal faces fierce opposition from many Democrats, labor unions and environmental groups. They said the TPP will kill U.S. jobs and benefit large, multinational corporations. 
 
 The AFL-CIO announced Thursday it would launch a six-figure ad buy to fight the fast-track bill in a series of digital ads targeting 16 senators and 36 House members. The campaign could expand to newspapers and television, the organization said. 
 
 The fast-track bill, formally known as "trade promotion authority," was negotiated for months between Hatch and Wyden, with the Democrat under increasing pressure from liberal groups not to sign onto the legislation. 
 
 [White House counts on Sen. Wyden to deliver on a trade deal] 
 
 Presidents have over the past 40 years enjoyed fast-track powers on trade, but the powers have not been renewed since they expired in 2007 under George W. Bush. Obama and his aides have said they need the authority because other countries are unwilling to agree to final terms if they believe Congress will amend the pact afterward. 
 
 "We must speak with one voice in our demands and provide assurance that we will deliver what we promise," Hatch said. 
 
 Wyden fought for, and won, a number of provisions aimed at ensuring greater public transparency in the trade negotiations, as well as a key provision that would allow the Senate to turn off the fast-track authority if the Obama administration fails to live up to certain requirements during the negotiations. 
 
 "One issue that has come up again and again is the excessive secrecy that seems to have accompanied so much of this debate," Wyden said Thursday. "American trade policy needs to be debated openly." 
 
 The bill also includes provisions mandating that the administration pursue protections for workers and the environment and a stipulation that U.S. negotiators make human rights a priority, though that provision lacks specifics. 
 
 Politically, the legislation places Obama squarely against a majority of House Democrats and a large bloc of Senate Democrats, many of whom believe previous trade deals hurt U.S. workers. In a sign of how difficult the fight will be, Sen. Charles E. Schumer (D-N.Y.), who is expected to take over as leader of his party in the Senate in 2017, said he was skeptical of the TPP because it lacks protections against currency manipulation. 
 
 "All evidence I’ve seen is that this hurts middle-class incomes," he said at a hearing before the trade bill was introduced. "I can’t be for it." 
 
 Later Thursday, Schumer said that support from him and many Democrats would depend on a separate currency manipulation bill that Hatch has promised to bring up, saying he would not settle for a "milquetoast" measure. 
 
 Hatch made clear that he'll give Schumer the chance in committee, but that TPP would move on its own track. "We'll do a bill on currency manipulation, but it can't be part of this, or it's dead. So we can't kill trade just because somebody wants one aspect or another," Hatch said. 
 
 Sen. Richard J. Durbin (D-Ill.), the minority whip, estimated that only a quarter of Senate Democrats were in the president's camp right now. He broke down his caucus ranks this way: "A fourth, hell no; a fourth, lean yes; and a big group undecided." 
 
 With most Senate Republicans likely to support the fast-track legislation, most corporate and union officials expect the Senate to clear the bill in May and set up a much bigger fight in the House, where the margins are incredibly narrow at the moment. 
 
 Several dozen House Republicans either come from manufacturing districts and do not support trade deals, or are just so opposed to giving Obama any new authority that they would vote no. That means Obama would need to deliver more than 30 Democrats to win passage in the House, which insiders on both sides of the aisle say is not guaranteed. 
 
 "This is wrong, and members of Congress will not stand for it," said Rep. Rosa L. DeLauro (D-Conn.), who has led the liberal opposition to trade deals. ||||| President Obama speaks at a news conference at the White House on Nov. 5, 2014. (Mandel Ngan/Agence France-Presse via Getty Images) 
 
 Note: This explainer (which is from April) deals specifically with TPP and TPA. For those interested in TAA, we've got that covered, too. See here. 
 
 I spend my life writing about politics. I also like math and data and so on. And yet even I find the discussion of the trade deal being considered in Washington to be hopelessly dull. (I say this sincerely.) But we are all adults, and we should be informed about what the government is doing. So allow me to do my best to outline what's being discussed in a way that will offer at least a 22 percent chance you'll stay awake for the entire thing. 
 
 Okay. Two separate things are being talked about, each of which is often referred to by an abbreviation, and the two abbreviations are almost identical. (We are starting off poorly.) 
 
 First, there's the Trans-Pacific Partnership, or TPP. This is the actual trade deal that President Obama is hoping to secure with a number of countries, including Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore and Vietnam. You can remember that TPP is the trade deal itself because TPP is like OPP, and the deal is all about getting other people's property. Specifically, the people of the Pacific Rim. 
 
 Then there's Trade Promotion Authority, or TPA. This is also known as "fast-track" authority because it gives the president the ability to negotiate a deal that will receive only an up-or-down vote in Congress. Without fast track, Congress can amend the terms of the deal. You can remember that TPA is "fast track" because when you T.P. a house, you are on the "fast track" to juvenile delinquency. Or you can just call it fast track, which is easier. 
 
 Fast-track authority doesn't apply to only one agreement. In the past, it has spanned presidencies, beginning in 1974 and lasting until the Clinton administration. It also existed during parts of both terms of George W. Bush's presidency. From the president's standpoint, fast-track authority is critical to negotiating agreements because he can negotiate in good faith -- what he says to his negotiating partners he's confident will be part of the final deal (if Congress approves it). 
 
 So that's TPP and TPA. Now let's talk politics. 
 
 Trade deals are often contentious, particularly among Democrats. (Last year, the National Journal called trade the "last major fault line" in the party.) Environmentalists often oppose the deals because they don't include heightened environmental protections. Labor loathes trade deals, having seen hundreds of thousands of manufacturing jobs go to Mexico in the wake of the North American Free Trade Agreement (also known as NAFTA) and because they want stronger worker protections included (in part, to ensure that overseas manufacturers aren't cutting costs on the backs of their workers). 
 
 [How to sound like you know what you’re talking about on trade] 
 
 But the business community -- and therefore most Republicans and pro-business Democrats -- loves these deals, because they open up new markets. (And, in the past, because companies have been able to cut costs by moving jobs to, say, Mexico.) This led to the unusual spectacle this week of the Chamber of Commerce, which opposed Obama's reelection, arguing in favor of giving Obama fast track and the AFL-CIO, which backed his reelection, arguing against it. 
 
 We should mention: Fast track is the actual political issue right now because Obama considers it essential for completing the TPP (yeah, you know me). He has been trying to line up Democratic support for reinstating the authority, but has had trouble getting some of his team on board. Last week, he had a big victory when Sen. Ron Wyden (D-Ore.) reached an agreement with Republicans for what he calls "smart track" -- fast-track authority overlaid with mandatory protections for workers and the environment. 
 
 The louder fight, as always, will be in the House. As you may have gathered above, many House Democrats have expressed reluctance to approve fast track. More than 120 signed a letter opposing TPA during the last Congress. And as The Post's Reid Wilson elegantly details, Democratic power centers have changed since NAFTA was passed in the 1990s, making the fight trickier. 
 
 So what, you might ask. If Republicans like the idea, doesn't Speaker Boehner have enough votes from his conference? And my response is: Has Boehner ever had a unified caucus? As usual, the most conservative wing of the House GOP is giving Boehner trouble. Earlier this year, a prominent tea party organization trumpeted that it was teaming up with labor to block fast track, yet another set of weird bedfellows in Trade Deal Hotel. The conservative opposition comes from a different place, though: The group does not support granting that much power to the president, particularly this president. A common argument is that fast track skips over the democratic process of Congress weighing in on an agreement -- which is true, but is also something Congress has overlooked in the past. 
 
 Hanging over all of this is 2016. You may remember several references above to NAFTA, the big trade deal in the 1990s that labor hates. You also may remember that the president who finalized that deal was a gentleman who went by the name of "Clinton." (Here's the Web page from his administration explaining what fast track is!) You also may have heard that his wife is running for president. 
 
 Hillary Clinton is in a tough spot. She seems eager to get the left-most wing of the party behind her, but it almost uniformly doesn't like the TPP. (Sen. Elizabeth Warren has been outspoken in her opposition, prompting an unusual rebuke from the president.) When Clinton was secretary of state, she backed the deal -- but she can easily point out that she was working for the guy who is so eager to see it pass now. She offered a tepid note of caution on the deal last week, including that she is worried about "currency manipulation" -- something that has been called a "poison pill" for a deal. (Meaning: If it's included, the bill is dead. You probably knew that, but we're just making sure.) 
 
 Jeb Bush has already attacked Clinton for her "flip flop" on the deal, because . . . he's on Obama's side? As we said earlier, the politics on this are weird. 
 
 So, that's where we are. Congress is expected to vote on the issue next month, meaning lots more time to hear about how all of this works. (And lots more time for 2016 candidates to try to beat each other up.) If you made it this far, if you read this far down, you deserve a reward. E-mail me, and I will e-mail you back a personal thank-you note. You deserve it. Being an adult doesn't have to be hard.
– One of President Obama's biggest goals for his home stretch in office took a big step forward today with a deal struck by leading Republicans and Democrats. It's regarding the Trans-Pacific Partnership, a proposed pact with 11 Pacific Rim nations that the Hill notes would be the biggest trade deal since NAFTA. In this case, the usual DC politics are flipped: Most Democrats oppose the president and most Republicans support him, reports the Wall Street Journal. Despite today's progress—it was introduced as "fast-track" legislation in the House and Senate—its ultimate fate is unclear in Congress. The New York Times predicts that for Obama, it will be "one of the toughest legislative battles of his last 19 months in office." Making it fast-track legislation means that lawmakers would vote yes or no on the deal once the US and the other nations agree on terms, but they would not be able to add amendments. That greatly increases Obama's chances of getting other nations—including Japan, Vietnam, Canada, and Mexico—to sign on, because they wouldn't have to fear later changes. A sign of the challenges supporters face: The AFL-CIO says it will spend six figures on ads going after 16 senators and 36 members of the House, reports the Washington Post. The group is worried about the loss of US jobs, but Obama says the deal is necessary if America hopes to stay competitive against China.