Pro-gay marriage protester in front of the Supreme Court-Chip Somodevilla/Getty Images

I’ve been saying for some time now that Republicans are out of step with their fellow citizens and even the younger generation in their party. Now there is some powerful polling evidence to back that up.

My colleague Greg Sargent writes:

A new Quinnipiac poll out today drives this home with striking clarity: It finds that gay marriage has far greater support among constituencies that are growing as a share of the vote than it does with the public overall.

The poll finds that a plurality of Americans supports same sex marriage, 47-43. But dig into the internals and you find that the groups that increasingly make up the main pillars of the Democratic coalition support it in much larger numbers. Hispanics: 63-32. Young voters: 62-30. College educated whites: 59-32. White women: 50-40.

In other words, gay rights, like immigration reform, is increasingly popular among groups that Republicans must attract to win national elections. It is, I would suggest, a gateway issue that candidates must pass through to get a real audience with voters who have come to view Republicans with suspicion.

In the Quinnipiac poll Greg cites, Republicans oppose gay marriage by a margin of 69-23 percent. That however, may not account for another phenomenon: the generational shift within the GOP.

According to the group Freedom to Marry, two pollsters, one from President George W. Bush’s campaign and one from President Obama’s, find:

Among Republicans under age 30, 51 percent support the legalization of same-sex marriage in their state;

All major non-evangelical religious groups (white non-evangelical protestants, white Catholics, Hispanic Catholics, African American non-evangelical, Jewish) are ready to legalize marriage for same-sex couples;

Regardless of their position on the issue, most voters (83 percent) believe that same-sex couples will win the freedom to marry nationally.

It is noteworthy that even among those who oppose gay marriage seem to understand that they have lost the argument. The “problem,” if you will, is that the pocket of concentrated opposition to gay marriage — older white evangelicals — vote in strong numbers in GOP primaries. Now, to be blunt, I don’t think these people must pass away before the GOP can shift position on gay marriage. There are several better alternatives.

To begin with, if the GOP is successful in recruiting younger and more diverse voters and getting them to vote in the primaries, they will remake that primary electorate. If Sen. Marco Rubio (R-Fla.), for example, becomes popular with women, minorities and young people, those groups are going to be very comfortable with, and actually may demand, a more libertarian stance on gay marriage.

In addition, this is quickly becoming a moot issue. The Supreme Court, let’s assume, strikes down the Defense of Marriage Act; does a GOP candidate for Senate or Congress from, say, Maryland even have to opine on the topic? It’s the law of his state and the feds can’t do much about it. (Those who argue for a Constitutional amendment banning gay marriage are truly in never-never land. Where do they suppose the states to ratify this may come from?)

Conversely a Senate candidate from, say Texas, can say “Gay marriage isn’t legal in my state and I’ll defend Texans’ right to decide their own definition of marriage, but it’s not an issue for the feds.” (That actually is what Gov. Rick Perry was saying before he tried to run for president.)

For presidential candidates, the landscape will change even more in favor of gay marriage with each passing year, as more and more states pass gay marriage laws. Will most states have legalized gay marriage by 2016? Maybe not, but we will be getting there.

In short, what has been a part of GOP orthodoxy is no longer a majority position among the electorate and is quickly falling out of favor within the GOP. By 2016, I think it is entirely likely that several candidates not easily labeled as “moderates” or even “libertarians” will either take no position on or support a state’s rights position. Depending on the speed of state-level initiatives there may even be candidates who flat-out support gay marriage, or we may see a situation in which no serious contender favors “traditional” marriage as part of his or her agenda.

Presidential candidates, who in the GOP tend to be older, more experienced pols, are quite often lagging indicators on hot button issues. But even they, I strongly suspect, will catch up with the times by the next presidential race. If not, they will have bigger problems than even I imagined.

Jennifer Rubin writes the Right Turn blog for The Post, offering reported opinion from a conservative perspective.