Tonight at 9 pm, Mitt Romney and Barack Obama will face off in the first of three presidential debates leading up to the November 6 general election. Romney’s campaign has been sinking fast, with a slow drop in the polls since the conventions. With these debates as the last chance to turn things around, here’s what’s happening behind the scenes at the two campaigns.

Practice, Practice, Practice.

Romney’s campaign knows that these debates may be their last shot to recover from their ongoing slide, so they’ve been preparing for months. Luckily, Romney will be coming in hot. The candidate already has 23 debates under his belt this election cycle, thanks to the raucous primary battle.

Obama, meanwhile, has been understandably busy (trying to) run the nation (into the ground, depending on whom you ask). This weekend, the president flew to Las Vegas for a campaign rally, and followed this up with three days of intensive prep lead by his campaign director David Axelrod.

Given that Obama is ahead in the polls, the president won’t be pulling for a knockout, Instead, he’ll be trying not to let Romney land any blows, and hope that the Republican candidate trips.

Romney, meanwhile, has to go in for the kill. His team “has equipped him with a series of zingers that he has memorized and has been practicing on aides since August,” according to The New York Times.

The Format

The debate will have six fifteen-minute segments with all time moderated by Jim Lehrer. There will be no opening statements. Mitt Romney won a coin toss for the last closing statement.

The Stand-ins

To play Romney’s part during debate preparation, Obama’s team tapped another aloof, hard-to-love Massachusetts millionaire — Democratic Senator John Kerry. Obama and Kerry have only had one mock debate; others were scheduled but cancelled following the protests and embassy attack in the Middle East.

The ersatz Obama at Romney’s prep sessions has been Republican Senator Rob Portman from Ohio, who has played POTUS in at least three mock debates. Portman’s apparently doing a good job frustrating Romney. “We get the chance to debate one another, and after the hour and a half or so is over, I want to kick him out of the room,” Romney is quoted as saying in the New York Times.

Their Weak Spots

Obama never was the best debater, and he’s out of practice. He hasn’t debated since the 2008 presidential campaign, when Senator John McCain was a far easier opponent than Mitt Romney. Additionally, President George W. Bush offered an easy target for Obama to attack. This time around, he’ll be playing D for the first time. If he attacks Romney too hard, he might come off as hostile or bullying.

Romney, contrastingly, never had an easy time connecting with voters. Further, his campaign is coming off of a very rough September, in which the candidate took a beating for comments in response to the Libyan embassy attack and for the now infamous 47% video. Those are two sensitive, low-hanging fruits at which Obama is sure to aim some blows.

Goofs and Gaffes

Obama will work to cast Romney as an out-of-touch millionaire. Romney will be hoping that Obama comes off condescending or even hostile. Both will be working to goad the other into saying something stupid.

Need an example of what that might look like?

One of Romney’s worst stumbles during the primary debates was the “ten-thousand dollar bet” that he offered Governor Rick Perry over the veracity of Romney’s individual mandate record. Talking heads jumped on the figure, pointing out that what constitutes a drop in the bucket or Romney’s wealth is a huge figure to most working Americans.

Obama’s biggest ’08 debate blunder was a bit more subtle but arguably more destructive. Days before the New Hampshire primary, Senator Clinton was asked her thoughts on the “likeability gap” between her and Senator Obama. After she joked that it “hurt her feelings,” Senator Obama chipped in unhelpfully, “you’re likable enough, Hillary.” Days later, New Hampshire voters responded — they picked “likable enough” over “likable” and handed the state to Clinton.

The Expectations Game

As is typical before a debate, both campaigns are working to lower expectations ahead of Wednesday’s rumble. “Governor Romney, he’s a good debater. I’m just okay,” President Obama told an audience in Las Vegas on Monday.

This bizarro pre-debate pageant found Romney hyping Obama’s performance, a move intended to cast Romney as the underdog. Romney said on Fox News this week, “The president is obviously a very eloquent, gifted speaker — he’ll do just fine. I’ve, you know, I’ve never been in a presidential debate like this, and it will be a new experience.”

Overall, Romney’s team, is focused less on muting expectations about performance than impact. “Sometimes we expect a major breakthrough, but that doesn’t happen very often,” Senator John McCain said on CNN.

Meanwhile, Gary Johnson…

Though most voters don’t know it, there is a third candidate who will be on the ballot in at least 47 states in November — Libertarian Gary Johnson, who campaigned at NYU last month.

The debates are controlled by The Commission on Presidential Debates, a non-governmental body controlled jointly by the Democratic and Republican parties. The commission did not invite Johnson to participate, provoking an anti-trust lawsuit from the Johnson campaign. “Someone has to stand up and call this what it is—a rigged system designed entirely to protect and perpetuate the two-party duopoly,” his spokesman said. “That someone will be the Johnson campaign.” Johnson is suing under the Sherman Anti-Trust act, a century-old law banning unfair competition in the market.

Unfortunately, Johnson does not meet the Commission’s stated criteria for participation, which requires at least 15% support for a candidate in major polls. Right now Johnson is in the single digits.

Still, there was some minor impact on the debate after three sponsors pulled support from the broadcast following intense lobbying by libertarian and debate reform groups. Phillips Electronics became the largest company to decide not to fund what they called  “partisan politics.” They followed British ad firm BBH and the YWCA in ending their support.

The Commission, a nonprofit, depends on such corporate sponsorship.

Local’s Got You Covered

Make things a bit more interesting by following along with NYU Local’s Presidential Debate Drinking Game.

During the broadcast, Local’s resident politicos will be posted up in Brad’s, yelling loudly at the TV and the internet at large. Follow writers @99Brett, @arisayswhat, @avakiai and @jsuricz for live tweets from the Finney-fueled viewing fiasco. Politico did say “the debates will be decided on Twitter,” and who better than us to decide it?

Wrap things up with some bitter, hungover commentary tomorrow morning.

Then get ready to do it all again.