Newt Gingrich, who is surging in recent polls, Rick Santorum, Herman Cain, Ron Paul, Rick Perry and Michele Bachmann will appear Saturday at a forum in Iowa hosted by the state's leading anti-gay marriage group.

The Thanksgiving Family Forum will take place at the First Federated Church in Des Moines and is sponsored by The Family Leader. Co-sponsoring the event are CitizenLink, the lobbying arm of the Christian conservative group Focus on the Family, and the National Organization for Marriage (NOM), the nation's most vociferous opponent of gay marriage. Frank Luntz will serve as the forum's moderator.

Former Massachusetts Governor Mitt Romney was invited but is not expected to attend.

The Family Leader is helmed by Bob Vander Plaats, the Sioux City businessman who turned his attention to ousting three of the Iowa Supreme Court justices whose ruling brought gay marriage to the Midwest after he lost a bid for governor.

Vander Plaats has previously likened homosexuality to polygamy and adultery and has called gay people a public health risk worse than second-hand smoke.

During an appearance Friday on MSNBC, Vander Plaats forgave Gingrich for his marital infidelities, saying, “[T]he cornerstone at the heart of our faith is a thing called forgiveness.” (The video is embedded in the right panel of this page.)

Gingrich has yet to sign the group's 14-point anti-gay marriage pledge.