Of course, it's probable that Obama has long-supported gay-marriage but has only recently been able to say so. Moreover, the extent f his commitment to it should not be exagerrated: he supports gay-marriage but believes it should be a matter for the individual states, not the federal government. Which means, in effect, that he doesn't support gay-marriage as strongly as he supports almost everything else he believes in. An outbreak of Federalism! Whatever next?
Plainly, since 31 states have passed laws outlawing same-sex unions, Obama's position recognises the limits of what is politically feasible. And yet this is more than simply a question of pleasing a Democratic base that, in large part (though with some significant exceptions) was beginning to wonder when the President would come clean and catch-up with mainstream liberal thinking. As David Frum points out, it positions the Democratic party as the party of America's future:
Frum suggests that the Federalist approch to this issue cannot last; eventually there will be some kind of reckoning to solve the matter on the national level. He may well be right.“
[I]t locks in place for another generation the Brand ID of Democrats as the party of cultural modernity. This Brand ID fits uneasily upon the Democrats, for they are also the party of ethnic minorities and recent immigrants. With the president's statement, however, the modernists have gained the clear upper hand. Meanwhile on the Republican side of aisle, the cultural modernists keep losing. For all that people talk about the ascendancy of the Koch Brothers within the GOP, I'd venture that Charles and David feel about same-sex marriage almost exactly as President Obama does. Yet on this one, they lose.
Obama's declaration will not change many votes this November but it will rouse each parties base to open their wallets. For the GOP the problem is that, as Frum suggests, the party is trapped on the downward slope of this argument and that, the more the party protests about this, the more probable it is that, all things being equal, they damage the Republican party's appeal to younger voters (ie, those under 35) in ways that will harm the GOP beyond this November.
In 2004, you will recall, the simple version of the election result was that a coalition inspired by issures related to Guns, God and Gays ensured George W Bush had just enough firepower to defeat John Kerry. Though simplistic, there was something to that notion. Obama's support for same-sex marriage will tempt Republicans to try and repeat that trick this time. Whether it has quite the same muscle as it did eight years ago - and whether Mitt Romney can inspire the faithful - remains a more questionable proposition.
In terms of the electoral map, I suspect this announcement could possibly make Obama's life a little more difficult in North Carolina than it might have been without it but that this could be offset by making matters a little easier in Virginia. Elsewhere, in terms of the swing states, I think the impact (in as much as anything can be boiled down to a single-state or determining issue) is likely to be pretty limited.
Nevertheless, the GOP is, more than ever, the party of white, god-fearing men. That's a mighty important constituency but it's not enough and, as it declines in relative importance with every election cycle, the Republican party must win that constituency by ever bigger and bigger margins to make up for its relative weakness in other, growing, parts of the demographic balance-sheet. Perhaps this can be done but, at least as far as Presidential elections are concerned, it tilts the playing field ever so slightly in the Democratic direction.