Before his inauguration, President Barack Obama called himself a “fierce advocate of equality for gay and lesbian Americans.” Now, with the gay marriage issue percolating in state after state and with the Pentagon’s “don’t ask, don’t tell” policy ripe for repeal, it’s time for him to put some of his political capital where his rhetoric is.

On Wednesday, Maine became the fifth state to legalize gay marriage; similar legislation in New Hampshire has been sent to the governor. Politicians in Washington who want to avoid what they see as a dangerous controversy have a convenient escape: They can say that the marriage issue should be left to the states, and that the question of whether a legal gay marriage in one state should be recognized everywhere has already been addressed by Congress and ultimately will be settled by the courts.

But that’s a dodge, not a stance.

Favoring “civil unions” that accord all the rights and benefits of marriage — but that withhold the word marriage, and with it, I guess, society’s approval — amounts to another dodge. I’m concerned here with the way the law sees the relationship, not the way any particular church or religious leader sees it. Marriage is not just a sacrament but also a contract, and the contractual aspect is a matter of statute, not Scripture.

Obama took the “civil unions” route during last year’s campaign and has stuck with it. But if semantics are the only difference between a civil union and a marriage, then why go to the trouble of drawing a distinction?

Equality means equality, and either you’re for it or you’re not.

Obama sensibly advocates the repeal of “don’t ask, don’t tell.” He should press the case by publicly reminding opponents of letting gays serve openly in the military that their arguments — it would hurt morale, damage cohesion and readiness, — are often the same, word for word, as the arguments made 60 years ago against racial integration in the armed forces.

He should also make the obvious case that forcibly discharging capable, fully trained servicemen and servicewomen for being gay, at a time when our overstretched military is fighting two big wars, can only be described as insane.

What the president shouldn’t do is stay away from the marriage debate on the grounds that it’s not a matter for the federal government.

Public acceptance of homosexuality is still far from universal. But attitudes have changed dramatically — more than enough for Obama to speak clearly about a matter of fundamental human and civil rights.