In an otherwise insightful column on the enthusiasm gap between Republicans and Democrats (Republicans have an edge of 56 percent to 43 percent in expressing more enthusiasm than usual about the upcoming presidential election), Gerald Seib observes:

Moreover, the Republican intensity seems to be a kind of negative intensity: GOP supporters appear a lot more fired up about voting against Mr. Obama than they are about voting for any of his potential Republican foes. . . . It may be that the difference isn’t meaningful when it comes to Republicans’ chances of winning next year. But it also may be that the intensity is more durable if translated into support for somebody rather than just against somebody.

But where is the empirical data for the premise that positive intensity is better than negative intensity? There is none.

Moreover, the very reason Republicans are so enthusiastic about 2012 is not because they’ve all lined up behind a dream candidate. Hardly. But it is because they see a real possibility of getting rid of President Obama, whom they fervently believe is ruining the country.

There is nothing wrong or even unusual about focusing on the incumbent’s flaws. Indeed, presidential reelection campaigns are almost always a referendum on the incumbent.

And here is where the left and right’s narrative breaks down. Anti-Mitt Romney conservatives say the party won’t get behind him, and without that enthusiasm they can’t beat Obama. The Obama camp and its willing shills in the media say Romney can’t get more than 25 percent among GOP voters and will be a weak opponent. (Still, the Obama team is so confident it will face Romney that it’s already gone bonkers over an ad.) This is wishful thinking, of course.

The GOP will pick its nominee, when, by definition, a candidate gets the majority of the votes. And whoever gets that nod will have in excess of 90 percent of Republicans falling in line behind him. The people willing to sign on with someone not their first pick are the very people who are really enthusiastic about the election and very enthusiastic about getting Obama out of the White House. The rest of the ball game will be about the independents and moderate Democrats.

There, too, the GOP has the edge. The latest Gallup poll reports that Obama’s approval rating “has dropped the most — 10 percentage points, from 40% to 30% — among pure independents. These are the roughly 14% of national adults who neither identify with one of the two major parties nor indicate a leaning. Obama’s approval rating has declined by nearly as much — eight points — among moderate/liberal Republicans, from 29% to 21%. . . . Additionally, conservative Democrats’ views also showed little change — likely because their approval was already at a dampened 70% at the start of the year.”

It’s fashionable to say you can only win elections by getting people to vote FOR you. But in 2006 the electorate voted against the House GOP (the Democrats made only a feeble attempt to put forth a positive agenda), and in 2010 the electorate voted against the Democratic House while the GOP’s plans remained fuzzy.

Running against an incumbent consists of only two arguments: 1) The incumbent doesn’t deserve reelection; and 2) the challenger is an acceptable alternative. In 2012, Republicans have virtually a lock on the first. The only danger is picking a candidate so extreme or unqualified or flaky or untrustworthy that he can’t clear the “acceptable” bar in a general election. (The Republicans are fully capable of doing just that.) Barring that, the GOP’s chances of retaking the White House remain bright.