With more than 50 million people watching and the presidency at stake, the candidates will meet for their first debate on Wednesday at the University of Denver, and both are cramming like college students before an exam. But it is not enough to pore through the voluminous briefing books. Victory may come down to a single exchange, or a single impression, an answer that comes off as too edgy or, conversely, as too long-winded…

Mr. Romney’s team has concluded that debates are about creating moments and has equipped him with a series of zingers that he has memorized and has been practicing on aides since August. His strategy includes luring the president into appearing smug or evasive about his responsibility for the economy…

To prepare Mr. Romney, Mr. Portman has played Mr. Obama combatively, attacking Mr. Romney as a rich man who does not care about average Americans. Evidently, he has gotten under the candidate’s skin. “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,” Mr. Romney said recently.

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The Republican presidential nominee has spent at least eight days over the past month getting ready for the three debates against President Barack Obama. He’s holed up for hours on end with briefing books, top aides and his sparring partner, Ohio Republican Sen. Rob Portman, often at the expense of campaigning.

Romney began intense sessions Sept. 4 at an adviser’s home in Vermont. Those ran for three days and drew the campaign’s entire top echelon to a remote resort in the mountains. A few weeks later, top aides flew to Los Angeles for more practice. Romney has held debate practice at his Boston headquarters, and he spent part of last weekend at the Back Bay Events Center, where the auditorium holds 1,100 people…

To guard against his trouble spot, Romney’s sparring partner — Portman — has spent hours carefully weaving personal jibes into his answers during mock debate sessions in which longtime Romney adviser Peter Flaherty stood in for moderator Jim Lehrer.

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The debates didn’t sink him in 2008 — they were probably a net plus taken as a whole, his staffers believe — but this time around Obama’s bedrock political asset is his likeability and capacity to bond with middle-class voters. Hence the unwritten rule in debate prep sessions against Sen. John Kerry, Romney’s stand-in: Hold your ground, but no more sneers.

“This is not a guy who can hide his contempt, and the only thing that can really hurt is if he’s smug and thinks he’s got this in the bag,” said a Democrat close to the Obama campaign, echoing the sentiments of several other aides and advisers heading into Wednesday’s inaugural debate against Romney at the University of Denver…

Team Obama has faith in their candidate’s discipline, but there are concerns his attitude could lead to another Al Gore eye-rolling or George H.W. Bush watch-peering episode.

“He can’t be a bigger d—k than Romney,” summed up the Democratic insider, familiar with the preparations.

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First, the president begins a pattern of “ahs” and “uhmms” which are as embarrassing as they are revealing. The awkward pausing punctuated by these semi-stutters increases in frequency as the president senses his own flailing about.

Next, the president begins filibustering. His average length of answer in every press conference is already epic, but he has been getting worse as the presidency has dragged on. Pressers are not battles between the “reporters” and the president. Very few not named Jake or Ed bother the president with fastballs. The struggle is simply between the president and the effort he has to land the plane anywhere near where it took off, so far does he wander as he rambles through the minutes he is obliged to spend appearing to take questions.

The president will allegedly be subject to time limits on Wednesday night, but his contempt for most such rules almost guarantees he will blow through every limit and dare the moderator or Mitt Romney to challenge him.

If either does, we will be treated to “tell No. 4,” the president’s feigned outrage that anyone would interrupt or question him.

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Amid all the pregame coverage of the first presidential debate, don’t neglect the Twitter effect. The winner and loser could be decided and the post-game narrative and media coverage could be set before the candidates even leave the stage

Many national, state, and local political reporters follow each other on Twitter and have a continual conversation about the state of the race. During the debate, the online dialogue will only be heightened as reporters analyze President Barack Obama and former Gov. Mitt Romney in real-time. And once a particular storyline takes hold (whether it be focus on an answer, zinger, twitch, or tie color), it will likely only be cemented by subsequent tweets, blog posts, newspaper stories and cable news coverage.

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Mitt Romney needs to deliver a strong debate performance on Wednesday but will be hard-pressed to completely alter the trajectory of the campaign in one appearance, former Mississippi Gov. Haley Barbour (R) said Monday afternoon…

We still have five weeks… I would be surprised if 100 percent of that is achieved in just the debates,” Barbour said when asked if the GOP nominee could fix middle-class voters’ perception that he does not understand their struggles as well as flesh out more policy details during the three presidential debates.

“Romney has time both through the debates and in other ways to make the sale. I think the burden is on him — it’s his election to win, has been the whole time. He has to do it,” he added.

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