ANALYSIS

By Dan Balz

The Washington Post

WASHINGTON — Rarely has a vice presidential debate been as crucial as the one between Vice President Biden and Rep. Paul Ryan tonight will be. After Mitt Romney’s lopsided debate victory over President Barack Obama in Denver last week, the exchange will arrive at a fluid and potentially pivotal moment in the campaign.

For the Obama team, tonight will offer an opportunity to short-circuit the advances Romney has made since last week’s debate. For the GOP, Ryan will have a chance to piggyback on Romney’s performance and solidify the gains their ticket has made in recent days.

The stakes also are higher than usual because the participants have a standing beyond their roles as running mates. They are real players, not potted plants or a sideshow to the main event.

Biden is vice president and therefore fully accountable for what has gone right and wrong on Obama’s watch. He is a central player in the administration who has not shirked from offering the president unvarnished advice.

He also speaks with the credibility of someone who has been in public life for four decades, with wide experience in foreign and domestic policy.

Ryan too is more than just a vice presidential nominee plucked from obscurity to fill out a national ticket. The House Budget Committee chairman may have a limited public profile nationally, but he has served seven terms in Congress and, of far greater significance, his peers consider him the intellectual leader of the Republican Party for his work on the budget and the economy.

If you doubt that, recall this: Long before Romney was the GOP nominee, Obama was attacking Ryan and his fiscal blueprint, an early foreshadowing of the 2012 campaign that has come into clearer focus this fall.

Some vice presidential debates are mere entertainment relative to the overall race, enjoyable but incidental to the fundamentals of the campaign. That was certainly the case four years ago when the forum, which drew a huge audience, was all about Sarah Palin, whose candidacy had captured the imaginations of friends and foes alike.

But the outcome of that exchange — a tie or modest victory for Palin in the eyes of many pundits and a win for Biden according to the public — did nothing to shift a race that already had moved away from Sen. John McCain and safely toward Obama.

Tonight’s debate at Centre College in Danville, Ky., could be different.

National public polls show movement toward Romney since Denver. A Pew Research Center poll released Monday highlighted a big gain for Romney. Gallup began posting a sample of likely voters from its tracking poll, and Tuesday’s showed Romney leading 49 percent to 47 percent. Among registered voters, Obama was ahead 49 percent to 46 percent.

GOP enthusiasm is up, which is good news for Romney. But more evidence is needed to know how much the landscape in the battleground states has been changed by the debate.

CNN released a poll of Ohio Wednesday that showed two things — Romney has narrowed the gap there, but the president is still ahead among likely voters by 51 percent to 47 percent. Other battleground surveys are expected by week’s end, and they should give a clearer picture of the state of play.

Romney advisers say the key battlegrounds are now within the margin of error, a significant shift from two weeks ago, when Obama led in Ohio, for example, by six to 10 points, depending on the survey. They are far more bullish today than they were a few weeks ago amid Romney’s difficulties.