On Thursday night, when same-sex marriage in New York State was teetering on a razor’s edge, President Obama had a perfect opportunity to show the results of his supposed evolution on gay marriage.

Unfortunately, he did not take it, keeping his own views in the shadows. The next night the Republican-led New York State Senate, of all places, proved itself more forward-thinking than the president on one of the last great civil-rights debates in this nation’s history.

Speaking to the Democratic Party’s LGBT Leadership Council at a fund-raiser in New York, Mr. Obama ran through the many efforts he has made on behalf of gay rights, including his decision to end the government’s legal support of the Defense of Marriage Act, which forbids federal recognition of same-sex marriage. The act should be repealed, he said, since marriage is defined by the states.

Mr. Obama’s legal formula suggests he is fine with the six states that now permit same-sex marriage, and fine with the more than three dozen other states that ban it. By refusing to say whether he supports it (as he did in 1996) or opposes it (as he did in 2008), he remained in a straddle that will soon strain public patience. For now, all Mr. Obama promised was a gauzy new “chapter” in the story if he is re-elected, and his views remain officially “evolving.”