WASHINGTON -- Wednesday night's debate holds the potential to nudge the polling numbers in a race that has given President Barack Obama a narrow lead throughout 2012, but the chances of a debate that will turn the race upside down are slim.
Voters are expressing strong interest in watching the debates. A poll by Quinnipiac found that 93 percent of likely voters planned to watch at least some of the debate.
But while debate audiences are typically large, past history suggests that these questions can exaggerate the level of interest and viewership. Four years ago, for example, Pew Research found extremely high interest ahead of the first Obama-McCain debate -- 82 percent of adults said they were at least somewhat interested and 58 percent were very interested.
The audience for that first 2008 debate, 52.4 million Americans, was huge by the standards of contemporary television ratings, but it represented less than half of the 131 million Americans that cast a vote for president four years ago.
Despite Obama's expectation-lowering protests that he's just an "okay" debater compared to Romney, more than half of voters think he'll win the debates.
The Quinnipiac poll found that 54 percent of likely voters projected Obama would win, compared to 28 percent who thought Romney would, with other polling showing similar numbers. While only 2 percent of Democrats thought Romney would emerge ahead, 20 percent of Republicans gave the edge to Obama.
Winning the debate, however, may not translate into winning votes. Genuinely undecided voters, who are often less engaged by the campaign, are less likely to watch. Only 68 percent of all adults who identify as independents have any plan to watch, according to an online poll from YouGov. Most of those watching have already decided, and the majority are skeptical that anything said on stage could alter the race.
Only 11 percent of likely voters told Quinnipiac that the candidates were "likely to do or say anything during the debates" that would change their minds, with a slightly higher number -- 16 percent -- of independents envisioning potentially switching sides. Just 6 percent of Republicans and 9 percent of Democrats said they were likely to change their minds.
Another poll by NBC and the Wall Street Journal found that 62 percent of registered voters said the debates would be unimportant or just somewhat important to their decision.
Historical data bears this out. An analysis by University of Wisconsin-Milwaukee political science professor Thomas Holbrook found that polls swung by an average of less than 1 percent post-debate in the past six elections.
The debate "comes at a helpful time for Romney to give him something else to talk about," Republican pollster Bill McInturff told NBC, cautioning that "it would take an episode of some magnitude to disrupt the structural lock that is shaping up on these numbers.’’
In other words: the proverbial "game changer."
Short of disastrous moments like Rick Perry's "oops," or Michael Dukakis' unemotional answer to a question about capital punishment, any shift is likely to be less dramatic. Similarly, debates rarely produce the sort of clear win that John Kerry experienced in 2004, when voters overwhelmingly judged him to be the better debater against President George W. Bush.
"The key factor will be whether one of the candidates can make small gains from each debate that, together, add up to something like a two or three-point gain during the debate period," Holbrook wrote. "I'm doubtful, but it could happen."
Rising a few points or even exceeding expectations in the debate could staunch the "Romney is fading" narrative that's been sustained since the conventions by a series of gaffes and an onslaught of polls showing him behind in key swing states. As George Washington University professor John Sides notes, how debates are covered can greatly affect who's perceived as winning.
Debates are seldom game changers, but given the still relatively close margin separating Obama and Romney, it might not take much to change this game.
CLARIFICATION: The Obama-McCain debate was four years ago, rather than eight.