A bunch of folks have already linked to the new Gallup poll finding that a majority of Americans support legalizing marriage equality for the first time.

But what I find most interesting about the poll is this: While the survey finds a large shift since last year in favor of legal gay marriage among Democrats and independents, the numbers haven’t budged by even one point among Republicans.

The poll finds that among Americans overall, the last year saw the largest annual jump yet in support for legalizing gay marriage — it’s up nine points, to 53 percent. Support jumped by double digits among Democrats (from 56 to 69) and among independents (49 to 59). For the first time a majority of independents supports marriage equality.

But among Republicans, support for gay marriage remains mired down at a measly 28 percent — exactly where it was a year ago.

The increasing separation between Republicans and indepenents on the issue is interesting on its own. But the larger story is what’s really striking. This year, multiple national polls are showing that for the first time, majorities of Americans have concluded that two consenting gay adults should have the right to marry and enjoy the same benefits of marriage that heterosexual couples do. As Steve Benen notes, “it’s exceptionally unlikely that trend will ever reverse — civil-rights trajectories simply never move that way.”

Andrew Sullivan, meanwhile, sees the shift in public attitudes as the result of “one of the most successful political and social campaigns in history.”

But the Republican rank and file just doesn’t seem prepared to evolve on the issue, even though the ultimate outcome now seems inevitable.