It must be frustrating for the right to realize that they’re losing the fight over marriage equality, and reversing the tide is pretty much impossible.

For the first time in Gallup’s tracking of the issue, a majority of Americans (53%) believe same-sex marriage should be recognized by the law as valid, with the same rights as traditional marriages. […]

This year’s nine-point increase in support for same-sex marriage is the largest year-to-year shift yet measured over this time period. Two-thirds of Americans were opposed to legalized same-sex marriage in 1996, with 27% in favor. By 2004, support had risen to 42% and, despite some fluctuations from year to year, stayed at roughly that level through last year.

There are, not surprisingly, partisan differences. Self-identified Republicans are no more accepting of marriage equality than they were last year, but support among Democrats and independents is growing quickly. At this point, the policy enjoys support from 69% of Republicans Democrats, 59% of independents, and 28% of Republicans.

The age differences are even more striking. Americans under 50 tend to strongly favor marriage equality, while those 50 and over do not. That, too, is bad news for the right, since it suggests it’s only a matter of time before the older generation passes and the position becomes a national consensus.

The larger trend is hard to miss:

What’s more, it’s not just Gallup — two other recent national polls showed most Americans support legal same-sex marriages.

I don’t imagine we’ll ever see 100% unanimity on this question. There’s probably still a tiny percentage of the population that still opposes people of different races or different religions from marrying, too.

But even the most radically anti-gay conservative has to realize that equality is inevitable. As the arc of history continues to bend toward justice, most of the country now believes two consenting adults should be legally permitted to get married if they want to. It’s exceptionally unlikely that trend will ever reverse — civil-rights trajectories simply never move that way. Society becomes less prejudiced, less hateful, and less bigoted over time.

And there’s not much the right can do about it.

To be sure, I don’t really expect conservatives to just throw in the towel — they have too much invested in this — but (a) winning elections by attacking gays is going to be a lot more difficult going forward; and (b) we can safely say marriage equality is only a matter of “when,” not “if.”

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.