When President Obama and former Massachusetts governor Mitt Romney take the stage at Hofstra University on Tuesday night for the second presidential debate, the pressure to perform will be squarely on the incumbent.

Thirteen days will have passed since Obama’s not-a-disaster-but-close performance in the first presidential debate in Denver, a showing that he and his campaign initially tried to shrug off as a draw but came around to admitting looked more like a rout for Romney.

The two weeks since have been filled with second-guessing — and second thoughts — from the Democratic base. Although Vice President Biden’s over-the-top performance in last week’s vice-presidential debate helped re-energize many of the party’s activists, there is still considerable anticipation/trepidation about whether Obama will (or can) perform better in this second showdown.

Although Obama’s ability to show some fight — or, at the very least, not look like he wants to get off the stage as quickly as possible — will be the dominant story line of Tuesday night, there are a few other interesting narrative strands to keep an eye on. We’ve plucked out three of those most interesting below.

●Obama the (more) aggressive: Obama is never going to give a debate performance like Biden turned in last week. (And that may be a good thing.) The president, for all of the time he has spent in politics, remains the college professor at heart — a cool and calculating clinician more than a heart-on-the-sleeve emoter when it comes to debating (and politics more generally). But, Obama and his team also know that another “does he even want to win” performance like he gave in Denver could cost him the race. And so, Obama is likely to use many of the attacks he didn’t in the first debate: Romney’s ties to Bain Capital, Romney’s “47 percent” comments and Romney’s unwillingness to put any meat on the bones of his tax plan. Remember, though, that Obama has never had to play the aggressor in a general election debate before. In the three debates with Sen. John McCain in 2008, it was clear that then-Sen. Obama of Illinois was playing it very safe, knowing that the Arizona Republican had to come out swinging in hopes of landing a blow that might change the trajectory of the contest. Although Obama remains a slight national favorite — and a slightly larger favorite in the electoral math — he will still feel pressure to play offense, a very unfamiliar position for him.

●Can Romney do it again?: It’s hard to debate that Romney’s performance in Denver turned the entire narrative of the presidential race around. But Romney’s strong showing in Denver also changed the dynamic for this week’s debate in New York — with the expectations of who will win reversed. (In the run-up to the first debate, polling suggested that large majorities expected Obama to win.) That means that Romney won’t benefit from the “he’s doing surprisingly well” story line. Nor will he probably get such a passive showing from Obama again. And while Romney’s performance in the first debate has clearly given him real momentum in the race, he has simply pulled himself closer to Obama, not passed him. To make up the ground he needs to in critical swing states such as Ohio, Ohio (and, yes, we know we mentioned Ohio twice — it’s that important), Virginia and Colorado, Romney probably needs another win in Tuesday’s debate — if not one as lopsided as he scored in Denver. Knowing that, and with Obama almost certain not to lie down as he did in the first debate, can Romney still shine?

●Town hall= tough(er) to attack: The setting for the second debate will be a town hall full of “average” Americans with CNN’s terrific Candy Crowley moderating. The questions in the debate will be asked by people in the audience, with Crowley following up or holding the candidates accountable as she feels it’s needed. That sort of format makes it tougher for the candidates to go harshly negative on each other than if it was simply the two of them standing behind podiums with Crowley seated at a table between them. The town hall backdrop puts a premium on trying to connect with the struggles, worries and hopes of the person asking the questions, not scoring points on scripted attack lines — although there probably will be plenty of those, too. The bar to being seen as overly or unnecessarily negative is far lower in a town hall debate than in a more traditional setting, meaning that both candidates will need to walk a very fine line with their attacks.