In another sign that we’re finally starting to take the Constitution seriously when it comes to equal rights, New York has become the sixth, and largest, state to recognize same-sex marriage.

That’s largely because of the political leadership of Gov. Andrew Cuomo, New York City Mayor Michael Bloomberg and former President Clinton — plus the support of prominent Republicans, led by Dick Cheney, Barbara Bush and Laura Bush.

Notice who’s missing from that list: President Obama.

In response to my question at Monday’s White House briefing, press secretary Jay Carney gave two explanations.

One, the president believes this decision should be left up to the states. But, surely, we don’t let states decide whether or not to grant basic constitutional rights. We didn’t on civil rights, and we shouldn’t on same-sex marriage, either.

Two, by refusing to defend the Defense of Marriage Act and moving to get rid of "Don’t ask, don’t tell," the president has already demonstrated his commitment to gay rights. But on this issue, gay marriage, his position is still “evolving.”

Well, at least he’s not dead set against it. But that’s still not good enough.

On an important constitutional issue like this one, it’s time for the president to lead, not follow. How many states have to endorse same-sex marriage before President Obama makes up his mind?