DANVILLE, Ky. -- Vice President Joe Biden will take the stage Thursday night to debate Rep. Paul Ryan in a matchup that Democrats hope will restore some of the momentum they've lost since President Barack Obama's widely panned performance in last week's debate.

Republicans, meanwhile, want to bolster their own standing, which polls indicate has improved since nominee Mitt Romney's strong showing against the president. Romney's numbers have been rising in key battleground states.

"There's some thinking in conservative circles that Romney did so well and Obama did so poorly that a really good showing by Ryan could firmly establish a trend of momentum for the Republicans," said Keith Appell, a Republican consultant who advises conservative groups.

Even Democrats acknowledge that the stakes are higher now for Biden to deliver a solid performance.

"For Democrats, it's an opportunity to start the comeback narrative," said Fred Yang, a Democratic pollster. "It's a chance to restart, to acknowledge that we had a tough debate, but we've had some improving jobs numbers and we've got momentum heading into the next round."

The 90-minute faceoff at Centre College in Danville, Ky., which starts at 9 p.m., will focus on foreign and domestic issues. Martha Raddatz, chief foreign correspondent for ABC News, will moderate.

Biden has more foreign policy experience. But Ryan is likely to push Romney's charge that the administration has mishandled events in the Middle East, particularly the attack on the U.S. consulate in Libya that resulted in the deaths of four Americans, including the U.S. ambassador.

Biden is expected to cast himself as a champion of the working class and to portray his opponent as a far-right conservative and a member of the unpopular House of Representatives. He'll look to tie Ryan to his budget plan, which cuts into popular programs, and charge that Ryan wants to radically change Medicare and cut taxes for the wealthy.

Ryan will likely portray Biden as partner in a presidency that has failed to fix the economy and improve conditions for millions of jobless Americans.

Biden came off the campaign trail nearly a week ago to prepare, with mock debates using Rep. Chris Van Hollen of Maryland playing the Ryan role. Van Hollen serves on the House Budget Committee with Ryan, its chairman.

The campaign has even dispatched Obama's chief campaign strategist, David Axelrod, to Biden's debate preparation -- a move the campaign insisted had been in the works even before the first debate.

Ryan has spent five days on debate preparation. Standing in for Biden was attorney Ted Olson, the U.S. solicitor general under President George W. Bush, who successfully argued the contested 2000 presidential contest before the U.S. Supreme Court.

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