Romney signs marriage pledge

Former Massachusetts Gov. Mitt Romney has joined Minnesota Rep. Michele Bachmann and former Sen. Pennsylvania Rick Santorum in signing a pledge to oppose same-sex marriage on a number of specific fronts.

The three candidates signed the pledge advanced by the National Organization for Marriage, which has led national and state campaigns to limit marriage to a man and a woman. The signature of the front-runner, Romney, is a bit of a coup for the group, as he's been careful about committing to other pledges, including a broad promise to a socially conservative Iowa group that caused trouble for other candidates.

Romney, Bachmann and Santorum signed on to support a federal constitutional amendment defining marriage, to appoint federal judges who don't see a constitutional right to same-sex marriage and to back the Defense of Marriage Act.

They've also pledged to support a referendum on marriage in Washington and to establish a "presidential commission on religious liberty" aimed at protecting the rights of marriage foes to speak out.

The pledge is less meaningful for its direct consequences than for the fact that it fully commits the three candidates to the hottest front in the culture wars.