By Maggie Haberman and Glenn Thrush
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.
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.
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).
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.
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.
2. Can Ryan defend himself and the GOP ticket?
The Republican VP nominee has to pull double duty on the debate stage tonight.
After Romney earlier this week gave to The Des Moines Register a garbled response about abortion legislation as a priority in his administration — one that his spokeswoman had to promptly walk back — Ryan told reporters that he and his ticket mate are "unified" on the issue.
Except…they're not. A Catholic, Ryan has deferred to Romney's position, noting the president sets policy. But Ryan's own positions on the issue are more strict about curtailing the availability of abortion.
Ryan is not only going to have to show that he's nimble defending a budget map he crafted but that Romney says is not entirely his own plan in key respects, though the presidential nominee hasn't offered substantive details about ways in which they differ.
Ryan's challenge is to defend the Republican ticket without seeming inauthentic in doing so.
3. Will Ryan let his feel-your-pain flag fly?
In repeated interviews, including one with Fox News's Chris Wallace, Ryan has dodged questions about the GOP ticket's budget plan by saying there wasn't enough time to explain it. In other interviews, he's said he doesn't want to get all "wonky."
That's a bit harder to argue on a debate stage, especially after the numbers-laden and surprisingly substantive first presidential debate.
Romney's response to Jim Lehrer on the tax plan questions, and to Obama, was that the president wasn't telling the truth. Ryan is likely to answer in a version of the same way, but people who are actually watching the debate and who hear that the congressman is also the House Budget Committee chairman will expect to hear more.
Ryan is most comfortable giving a PowerPoint presentation, and while he won't literally have one to display on the debate stage, he may have to act like he does.
Equally important for Ryan will be rising to the type of feel-your-pain moment that is a Biden trademark, and the reason the Obama team has dispatched the vice president on the trail so regularly.
Whether Ryan can show that kind of emotion, especially if Biden ups the ante by doing it himself, is a key question.
Also critical — how Ryan handles the inevitable Medicare, Medicaid and senior citizen-related attacks that Biden will launch. The budget chairman is already the face of "Mediscare" for Democrats, and how he engages the issue onstage will be important to watch.
4. Good Joe v. Bad Biden
Biden is flat-out the best debater in the 2012 campaign this side of Mitt Romney — more comfortable and limber at the lectern than his own boss, according to Democrats who get paid to prep candidates. And four years ago, he delivered what was arguably the most effective, and restrained, performance of his four-decade career against Sarah Palin in the 2008 vice presidential debate.
True, the bar was lower for Biden then than now: Palin was in way over her head on policy issues, Democrats had George W. Bush to kick around and Biden showed off an easy mastery of foreign and domestic affairs (even if he memorably, if mistakenly, predicted Obama would never agree to an Iraq-style surge in Afghanistan).
Biden proved, as he has during his best moments, that he could speak movingly to the concerns of real people. The moment that really stood out in the 2008 debate: Biden's discussion of what it was like to take care of two critically injured sons alone after his wife and 1-year-old daughter were killed in a 1972 car crash.
"The notion that somehow, because I'm a man, I don't know what it's like to raise two kids alone, I don't know what it's like to have a child you're not sure is going to — is going to make it — I understand," he said, as everyone at the venue held their breath. "I understand as well as, with all due respect, the governor or anybody else, what it's like for those people sitting around that kitchen table. And guess what? They're looking for help. They're looking for help."
That's the Biden Democrats want to see. The one they don't want to see is the one prone to veer off message badly, freelance or talk out of his hat.
Remember the veep's off-the-cuff pre-endorsement of gay marriage earlier this year that created an angry rift inside the administration? Or the "big f—-ing deal" moment that stole Obama's thunder during the signing of the historic health reform act? Or back in the fall of 2008, when Biden gave John McCain a major opening by declaring that the then-freshman senator from Illinois would get hazed by some nasty world leader, like Khrushchev challenged JFK? Or…
One Democratic aide, speaking on condition of anonymity, said that despite the weeklong prep, Biden was like a "box of Cracker Jacks — you never know what prize you're getting till you rip it open."
If there's any consolation, it's that polls show Biden is poised to play the role inhabited by Dick Cheney in his 2004 debate against a fresh-looking John Edwards — the elder statesman, well-known but not well-loved nationally, with fairly low expectations among the undecided voters who matter most.
5. How will foreign policy play?
The expectation heading into this week is that Biden would rely on foreign policy as a way of underscoring the stature gap between him and Ryan — as well as a difference in gravitas.
To that end, Romney, in a CNN interview two days before the debate, set the expectations about as low as possible with this statement: "This is, I think, Paul's first debate. I may be wrong. He may have done something in high school, I don't know."
That's perhaps not the most helpful comment for a candidate whose youthful appearance has continued to concern Republicans. And Ryan has actually been in eight debates with congressional challengers.
The lack of foreign policy experience on the GOP ticket has caused some concern for Republicans for a while, even as they say publicly that it won't be determinative because this is not the signature issue this cycle.
It's almost a given that Biden will recite some version of "Osama bin Laden is dead and General Motors is alive."
But the vice president is also going to be trying to make that case as the administration's explanation of what happened in the lead-up to the lethal violence in Benghazi on Sept. 11 has shifted repeatedly.
Ryan will almost certainly push back on Biden over that — as well as how it relates to overall criticisms of the administration's policies in the Mideast and how the White House has handled the aftermath of the Arab Spring.
The devastating events in Benghazi almost certainly give Ryan a toehold on a topic that has favored the Democratic ticket so far this cycle.
Maggie Haberman and Glenn Thrush are reporters for POLITICO.com. POLITICO and ABC News 4 have partnered for the 2012 presidential campaign cycle.