Early last year, I noted that Obama’s political advisors were tilting toward what I called a “Colorado strategy” for the reelection campaign. Their focus was on an emerging new Democratic majority—a coalition of young people, minorities, unmarried women, and upscale professionals. This tilt would come, I noted, at the expense of the “Ohio strategy”—my shorthand for an effort focused on retaining support from white working class voters…

One thing is clear: Obama’s decision aligns the Democratic Party with the demographic future of the country. Young adults overwhelmingly support gay marriage, and they’re sure to win the fight by outliving their older adversaries. The only question is whether the future is now. There’s reason to believe it may not be: In 2008, Obama received 20 percent of the conservative vote, accounting for about 7 percentage points of his overall 53 percent share of the popular vote. (By contrast, McCain received only 10 percent of the liberal vote, accounting for only 2 points of his overall share.) Conservative democrats, in other words, provided the decisive margin in the last election—a margin that it’s not clear can be compensated for with additional liberals.