The National Organization for Marriage (NOM) will once again ask presidential candidates to sign a pledge to work against marriage equality.

“We'll have an announcement soon about our new presidential pledge that we will ask every candidate to sign,” NOM President Brian Brown said in a blog post. “It could be a game-changer in the presidential contest, because it is going to put candidates' feet to the fire.”

At least five candidates vying for the 2012 GOP nomination signed NOM's 5-point pledge, including former Massachusetts Governor Mitt Romney, former Pennsylvania Senator Rick Santorum, former House Speaker Newt Gingrich, former Minnesota Rep. Michele Bachmann and former Minnesota Governor Tim Pawlenty.

Those candidates promised to support a federal constitutional amendment limiting marriage to heterosexual unions, 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.

NOM's pledge came on the heels of a similar effort by the Iowa-based Christian conservative group The Family Leader.

Candidates who signed its pledge vowed not only to “vigorously” oppose marriage equality but to be faithful to their spouses. It also ironically asked candidates to have “respect for the marital bonds of others.”