One thing we can reliably expect in any presidential campaign is that each side will complain that the other side's attacks are beyond the pale of civilized politics. Back in August, New York magazine writer John Heilmann tweeted "Truth: 2012 will be most negative pres campaign of our lifetimes" (I ridiculed the notion here). News flash: Campaigns often involve candidates criticizing each other, and this one will be no different. So Ben Smith explains that once again, Barack Obama is preparing a relentlessly negative campaign that will nonetheless not leave him tarred as a meanie. This will be accomplished through some combination of grand master-level jiu-jitsu and hypnotism:
Attack politics, of course, are more the norm than the outlier in American politics. But while slash-and-burn attacks typically damage both candidates—see, for instance, George Bush's low approval numbers when he was re-elected—Obama has so far pulled off the difficult trick of remaining broadly personally popular even as Americans are unhappy with some of his policies and with the direction of the country, and taking little blame for tough tactics.
George Bush's low approval ratings had nothing to do with him criticizing John Kerry -- you might remember that there was a weak economy and a disastrous war going on at the time. But anyhow, a couple of points are worth making. First, candidates rarely if ever get punished for being critical of their opponents. The only time that anyone suffers from delivering an attack is when the opponent successfully makes the attack itself the subject of a counterattack. This isn't easy to do, but it can be done, if the fact that Candidate A is launching vicious personal attacks on Candidate B can be presented persuasively as an indictment of Candidate A's character. But with a presidential campaign, unlike a race for a lesser office, voters get to know the candidates pretty well. It won't be possible to persuade people to believe something about Barack Obama that they never considered before. And "mean" just isn't one of the things people already think about him. So unless he starts insulting Romney's kids or something, it will be awfully hard to convince anyone that the conduct of the campaign is a reason to change their votes.
Second, the candidate remaining above the fray while his surrogates do the real nasty attacking is how most presidential campaigns are waged. The trick is to have aides and allies go out and say the really nasty stuff, while the candidate says things that remind voters of the really nasty stuff, while sounding like a basically polite person who just has some disagreements with his opponent. That's not just what Barack Obama has done and will do, but what most candidates do.
You can accomplish that in a presidential campaign because there is room for lots of surrogates speaking on your behalf. If you're running for Congress, reporters aren't going to write hundreds of stories about what your campaign manager or other friendly politicians think of the race, complete with lots of quotes allowing them to rip the stuffing out of your opponent. But presidential campaigns do offer plenty of those opportunities, so campaigns try to make the most of them. Some do it more deftly than others, but they all do it.
Finally, it's important that we keep in mind that there is nothing wrong with being "negative." It's OK for a candidate to criticize his/her opponent. If the criticism is accurate, fair, relevant, and not overly personal, then it ought to be part of the debate. Those are the criteria that matter. A race in which both sides only talked about themselves would be both boring and uninformative. It's perfectly fine for Rick Perry to say that the health-care plan Mitt Romney passed in Massachusetts is incompatible with Republican values. It's perfectly fine for Mitt Romney to say that Barack Obama's record of killing terrorist leaders and extricating America from endless wars indicates a troubling lack of unthinking belligerence. And it's perfectly fine for Barack Obama to say that Mitt Romney seems to shift his positions on issues to suit political expediency. All of those criticisms, whether you find them persuasive or absurd, have at least something to do with what the next presidency will be about.