Rick Perry, Republican candidate for president, has signed a pledge promising to oppose gay marriage.

The National Organization for Marriage (NOM) announced Perry, the Christian conservative governor of Texas, had joined GOP candidates Minnesota Rep. Michele Bachmann, former Massachusetts Governor Mitt Romney and former Pennsylvania Senator Rick Santorum in signing their pledge. Former Minnesota Governor Tim Pawlenty also signed but has since dropped out of the race.

“Kudos to Gov. Rick Perry for making it clear: he's a marriage champion!,” said Brian Brown, president of NOM. “The purpose of NOM's Marriage Pledge is to move from vague values statements to concrete actions to protect marriage. Gov. Perry joins Michele Bachmann, Mitt Romney and Rick Santorum as a signer of NOM Marriage Pledge. By doing so, Perry makes crystal clear that, contrary to the conventional wisdom, gay marriage is going to be a bigger issue in 2012 than it was in 2008, because the difference between the GOP nominee and Pres. Obama is going to be large and clear. We look forward to demonstrating that being for marriage is a winning position for a presidential candidate.”

Candidates who sign NOM's 5-point pledge promise to support a federal constitutional amendment banning gay marriage, defend the Defense of Marriage Act (DOMA) in court, appoint judges and an attorney general who will “respect the original meaning of the Constitution,” appoint a presidential commission to investigate the “harassment of traditional marriage supporters,” and back legislation that would allow a ballot question on the issue for voters of the District of Columbia

(Related: NOM calls on Herman Cain to sign anti-gay marriage pledge.)