Despite the conventional wisdom about the power of incumbency, the first debate is always harder for a sitting President to prepare for and execute than for a challenger. For one thing, unlike a challenger who has just emerged in fighting trim from a nomination battle (and all the forums, debates and confrontational exchanges that come with it), the incumbent has had far less practice and time to devote to purely political theatrics. Perhaps even more important is that sitting in the Oval Office does not keep you loose; by its nature the job makes the person who bears that responsibility more sober, cautious, and deliberate. A President running for re-election has just spent four years growing into the reality that a careless word or unevenly amplified tone can be the butterfly wing flapping in one place that causes a typhoon somewhere else. A challenger who is already being elevated just by being on the stage has the advantage in that first encounter.

More specific to last night, because so much of the electorate is already locked in on which candidate they truly despise, the sliver of voters available to persuasion was narrow going into the debate. Undecided voters are often swayed more by horserace analysis in the media than by what candidates actually say or do, so Mitt has changed the game just by giving Joe Scarborough and Peggy Noonan something to write home cheerfully about. That narrative – Mitt Finds His Voice! Obama Stumbles! Game On! – will surely affect how some of those undecided voters interpret the momentum of the race. We’ll see how much the needle moves in the next several days. Yet because there is so much immediate and obvious focus on how much the debate helped Romney and how much it hurt Obama, it’s worth thinking about some underlying issues that may end up mattering more on November 6th than the morning-after impressions driving the analysis right now.

The most interesting questions to me are counter-intuitive: does Romney’s success last night create a more treacherous path from here? Could Obama’s unexpectedly small performance help the president?

Romney, already a candidate laboring under a perception that he operates with a peculiar relationship both to the facts and to his own words and record, will now come under new scrutiny. The fact-checkers have today undermined Mitt’s claim about the $716 billion in Medicare he says he will protect from the President’s budget knife. Not only is the figure mischaracterized – the money is culled from scheduled increases in payments to providers, not funds for the benefit side – the same savings is part of the budget put out by his running mate, Congressman Paul Ryan. Even if you accept Romney’s argument that the cuts in payments will result in the denial of service from the affected providers, the same would be true for his own plan. Ironically, it is one of the only spending cuts the GOP team is prepared to specify.

Getting busted on such a slippery tactic is bad enough, but it underscores the faster water the GOP nominee is about to get into: on this and other responses from last night (such as his most recent plans for the tax code), Romney is now vulnerable to the problems that devastated his campaign for the past several weeks. The same guy who gutted himself with a video from a private fundraiser -- where he dismissed 47% of Americans as moochers who will never accept responsibility for their own lives -- will now have to endure video of his previously opposing statements. Advertising can effectively show earlier versions of the candidate debating himself from Wednesday night, and not just marginal changes in policy positions. Some of the shifts Romney made last night were in the area he described as “core values.” All of this will re-energize the question of Romney’s character and his willingness to tack with prevailing winds. This line of attack – demonstrating a stunning capacity for personally deceitful expression on television – will be powerful enough on its own. The bigger problem is that most voters already don’t like or trust Romney, and this could convert what was apparently his finest hour into a reminder of their initial impressions.

What about the President, who most voters do like even if they are disappointed that so little progress has been made in the last four years?

The Vice-Presidential Debate on October 11 will place Ryan under enormous pressure to finally get specific about taxes and spending cuts while at the same time forcing him to defend himself and Romney from Biden Unbound. The effects of that debate, combined with the power of the inevitable advertising narrative on Romney’s political character, will place Barack Obama in position to bounce back. Remember that this next “debate” will be a town hall format. Romney will be handcuffed with advice against behaviors or prevarications that will create the appearance that he is rude or dishonest directly to a voter. Because of widespread criticism of last night’s moderator Jim Lehrer, the moderator for the next event will be primed to respond swiftly to either candidate for ignoring agreed-upon rules. The media will promote and stage the event as a rematch. Republicans will be expecting Romney to repeat his earlier performance, and voters who supported Obama in 2008 – especially independents -- will be looking for the guy they fell in love with.

These circumstances could work in Obama’s favor, but only if he brings his A game. Mitt Romney will be ready too, and he demonstrated in Denver that his own game can be formidable. The viewing audience will be enormous and the stakes higher than ever, so expect something special.