All’s fair in love and war — and politics. But here’s a move many voters might not be thrilled about: Mitt Romney’s campaign for governor tried to make political hay out of the Massachusetts Gay & Lesbian Political Caucus’s endorsement of Treasurer Shannon O’Brien on Tuesday. When O’Brien slightly broadened the scope of her public comments about gay marriage, Romney’s campaign pounced on the comment as a " flip-flop. "

Here’s what happened. At the downtown Boston event accompanying the endorsement, O’Brien went further on the question of gay marriage than she has in the past. Asked whether she would sign a piece of legislation authorizing gay marriage — a somewhat unlikely scenario given the iron grip that staunchly anti–gay marriage House Speaker Tom Finneran has over Beacon Hill — O’Brien, who so far has embraced only civil unions for gay and lesbian couples, said she would. " I am committed to making sure we have equal rights for gay and lesbian couples, and I will work to make those equal rights a reality, " O’Brien said. " If it gets to my desk, I will sign it. " Later in the day, her campaign manager, Dwight Robson, stood by her statement: " If the legislation passes it, which is an unlikely event, she will not exercise her veto powers, and she will sign the bill. "

To the Romney campaign, O’Brien’s statement represented a kind of political blasphemy. " Whether she’s changing her position on abortion, gun laws, or gay marriage, it’s clear that Shannon O’Brien has no convictions and will say whatever is politically convenient, " said Romney spokesman Eric Fehrnstrom. " Mitt Romney believes that marriage is a union between a man and a woman. " (Romney, for his part, on Tuesday received the endorsement of the Log Cabin Club of Massachusetts, a gay Republican group.)

O’Brien’s initial reaction to the allegation that she had flip-flopped was difficult to watch. " I don’t support gay marriage. I support civil unions, " O’Brien told Janet Wu of WCVB-TV after an event in Brookline. " If there were a piece of legislation that enhanced these rights, I would make a judgment about that at the time, but I support civil unions. " Then she found her footing, stating: " I believe the fight is going to be about civil unions. Most people at this point in time do not support gay marriage. "

But the Romney campaign is making a tempest out of a teapot. O’Brien’s answers Tuesday were entirely consistent with her position. After all, the reason O’Brien supports civil unions — and not marriage — is political pragmatism. The public, she believes, is not ready for the marriage fight. She said as much Tuesday. Says Robson of O’Brien’s stance: " Not only does she support it, but she thinks it’s achievable. "

It’s certainly a position that’s more welcomed by advocates of gay marriage than Romney’s stance in favor of mere domestic-partnership benefits. Describing it as a flip-flop " is an absolutely unfair characterization because Shannon O’Brien has never said she was opposed to marriage. Shannon has already said she is a realist, " says Josh Friedes, the volunteer political director of the Freedom to Marry Coalition, which also endorsed O’Brien this week.

As their varying positions on the civil-unions issue demonstrate, there are key differences between Romney and O’Brien. That O’Brien, in a perfect world, would sign marriage legislation is encouraging. Too bad she feels political circumstances dictate she cannot support the move more wholeheartedly.