Vice President Joe Biden, Republican Rep. Paul Ryan take the debate spotlight for a night

DANVILLE, Ky. — Vice President Joe Biden and Republican Rep. Paul Ryan seized the campaign spotlight Thursday night for a 90-minute debate, their only faceoff of the 2012 race for the White House.

The encounter between the 69-year-old vice president and 42-year-old Wisconsin congressman was a high-profile interlude between last week's race-altering debate featuring President Barack Obama and Republican Mitt Romney and next Tuesday's return engagement.

Romney has gained ground in national and battleground-state surveys in the week since he shared a stage with the president, and even Obama has conceded he performed poorly.

Mocking recent changes in Romney's rhetoric, Obama told a Miami rally on Thursday, "After running for more than a year in which he called himself severely conservative, Mitt Romney is trying to convince you that he was severely kidding."

Romney visited with 93-year-old evangelist Billy Graham in North Carolina — 'Prayer is the most helpful thing you can do for me," he told the evangelist — before an evening rally in Asheville.

For Biden, Thursday night's debate was his first since the 2008 campaign, when he shared a stage with Sarah Palin, then John McCain's running mate.

Ryan spars frequently with Democrats during debates on legislation on the House floor and in the House Budget Committee, which he chairs, but not in a one-on-one encounter covering 90 minutes and a virtually unlimited range of topics.

For all their differences, the two men shared a common objective, to advance the cause of their tickets in a close race for the presidency — and avoid a gaffe that might forever seal their place in the history of debates.

Romney's choice of Ryan as running mate over the summer cheered conservatives in the House, many of whom regard him as their leader on budget and economic issues. The seven-term lawmaker has authored a pair of deficit-reducing budgets in the past two years that call for spending cuts and changes in Medicare, blueprints that Republicans passed through the House and Obama and his allies in Congress frequently criticize. He also champions a no-tax increase approach to economic policy.

As a senator before becoming vice president, Biden was chairman of the Foreign Relations and Judiciary committees, and he has long experience in national security issues. More recently, he was Obama's point man in arduous, ultimately unsuccessful negotiations with Republicans on steps to cut the deficit.

Both Ryan and Biden held extensive rehearsals, with stand-ins for their opponents.

Biden turned to Rep. Chris Van Hollen, D-Md., who is well-versed in Ryan's policy views from his tenure as senior Democrat on the Budget Committee.

Ryan's foil in rehearsal was former Solicitor General Ted Olson, a skillful courtroom advocate.

Martha Raddatz of ABC News had moderator duties.

After they meet next week in Hempstead, N.Y., Obama and Romney will have one more debate, Oct. 22 in Boca Raton, Fla.

Associated Press writers Philip Elliott in Kentucky, Ken Thomas in Florida and Kasie Hunt in North Carolina contributed. Espo reported from Washington.