Maryland Governor Martin O'Malley and former RNC chief Ken Mehlman back a new campaign to frame the case for legalizing gay marriage as an issue of commitment, not rights.

The Commitment Campaign launched Monday by the Third Way, a centrist Democrat group, is an effort to emphasize commitment over rights in the gay marriage debate.

“If you know only three things about advocating for marriage to the middle, they are the three lessons in this fact sheet. The most important lesson is that for the middle, marriage is about commitment – not rights,” a fact sheet on the campaign states.

The group's message is that the middle is uncertain about why gay couples want to marry.

“Americans in the middle place commitment at the heart of how they see marriage.”

According to Third Way, research shows that people who think gay couples want to marry for reasons of love and commitment are more likely to be comfortable with marriage.

“In this fast-evolving issue, we're all searching for common ground,” O'Malley, who is behind an effort to legalize gay marriage in Maryland, told USA TODAY. “And the way to have a conversation with those who would be inclined not to support marriage equality is to search for those common values that we share.”

Also supporting the campaign are Rhode Island Governor Lincoln Chafee and former New Jersey Governor Christine Todd Whitman.