9 p.m. ET all across the dial and streaming live at C-SPAN.org. Yesterday’s WSJ/NBC poll had 22 percent of likely voters saying that the debates will be “extremely important” to their vote. Today, Rasmussen finds 17 percent saying they’ll be “very important.” Either way, you’ve got roughly one-fifth of the electorate signaling some willingness to shift based on what happens tonight (and at the next two face-offs) in a race that’s statistically tied at the moment and arguably only now just beginning. To paraphrase “Honest Joe,” this is potentially a big effing deal.

Also a big effing deal? The media’s post-debate “narrative-building”:

Consider this experiment. In 2004, Kim Fridkin and other researchers at Arizona State University showed people footage of the third presidential debate, the debate plus 20 minutes of post-debate commentary on NBC, the debate plus 20 minutes’ time to read commentary on CNN.com. So who won the debate, Bush or Kerry? It depended on whether you watched the news…

People watching the debate tended to think that Kerry had won, as did those who read analysis on CNN. But those who watched the NBC post-morten had the opposite impression. Fridkin et al. write:

“Our findings suggest that voters’ attitudes are influenced by the arguments presented directly by the candidates during the debate as well as by the media’s instant analyses of the candidates’ debate performances….the impact of the candidates’ messages was often altered by the media’s instant analyses.”

The idea of NBC boosting Bush doesn’t compute for me any more than it does for you, but there you go. It’s not just the post-debate yammering that might influence viewers, either:

Through the art of video production, one candidate can be portrayed more favorably than the other. On October 7, 2008, then-Sen. Barack Obama and Sen. John McCain met for the second of three presidential debates. The format was a town hall debate. Both men roamed the floor and locked eyes with the audience members who asked questions. Numerous cameras were placed around the room to capture the candidates regardless of where they stood.

While equal time was given to each man for questions, the audience, when viewing the televised debate, experienced subtle differences in the camera angles for each candidate. Typically, when Obama spoke, the camera displayed a close up, eye-level image, filling the frame with his upper chest and face. This presented to the viewer a strong image of Obama. In contrast, when McCain spoke, the camera often showed a waist-up, medium shot, filling the frame with as much background as McCain himself. These shots made McCain appear small, which was exaggerated from time to time by camera angles that looked down on him. In addition, because of the wide shots of McCain, Obama had more face time on camera, as he was often shown in the background when McCain answered a question.

No one expects Romney to get a fair shake tonight in the aftermath, but one potential complicating factor is that not all of the media’s biases are strictly ideological. Ross Douthat (and Jon Chait) made a fair point recently about how their bias towards horse-race coverage casts a shadow of hopelessness over the candidate that’s fallen behind in the polls. Highly motivated, strongly partisan voters won’t care about that but low-information undecideds who pay attention only sporadically may be led to perceive the trailing candidate as, in Chait’s words, “faintly ridiculous,” which destroys the air of presidential viability that he’s trying to build. In Romney’s case, the ideological and horse-race biases overlap to work against the GOP, but they don’t always: John Cook of Gawker argued a few days ago that the media’s doing to Romney what it once did to both John Kerry and Al Gore, namely, pigeonholing him as a weird, stiff, hapless loser because his slight personal awkwardness is an obvious contrast with the confident charm of his opponent. It’s all about the narrative, and if they’ve got a narrative staring them in the face involving a guy who’s good at retail politics and a guy who’s not so good, that’s one that they’re going to grasp.

The punchline is that the media’s also biased for professional reasons towards having an exciting race to cover, and a post-debate “Romney comeback” narrative would serve that end. I’m not expecting it — I think ideological interests will trump all given that the race is so close — but if Mitt is sharp and composed, which he’s likely to be, you may see some “he helped himself tonight” chatter later even if there’s a reluctance by the press to pronounce him the winner. If you’re interested in watching the narrative sausage being made in real time, I recommend opening up a separate tab and following this feed of political journalists compiled by Matt Lewis. As with all Twitter communities, most of those people follow each other so there’ll be a plenty of perception insta-reinforcement afoot.

Tonight’s debate is supposed to be devoted to domestic policy but Libya likely will be mentioned. So will George W. Bush’s record, maybe by both sides. The 2007 Obama speech at Hampton U likely will not. Here’s the handy dandy Hot Air/Townhall Twitter widget, which should be buzzing until the wee hours. Enjoy.

Tweets from @erikajohnsen/townhall-hotair