Bob Vander Plaats has predicted a surprise win in Iowa for Rick Santorum.

The CEO of The Family Leader recently endorsed Santorum's presidential bid.

(Related: Rick Santorum: Bob Vander Plaats asked for money to promote endorsement.)

Vander Plaats is best known for leading last year's successful campaign to oust three of the seven Iowa Supreme Court judges who overturned the state's ban on gay marriage in 2009.

Santorum, along with Minnesota Rep. Michele Bachmann and Texas Governor Rick Perry, signed the group's controversial 14-point anti-gay marriage pledge, which asks each presidential candidate to “vigorously” oppose marriage equality, be faithful to his or her own spouse, vow to protect women and children from pornography and reject Sharia law because it is a “form of totalitarian control.”

During an appearance on Fox News, Vander Plaats told host Gretchen Carlson that Santorum, who in recent days has surged in Iowa polls, would be the surprise winner of Tuesday's Iowa caucuses.

Of the last-minute surge, Vander Plaats said: “Rick Santorum had a lot to do with it. He did visit all 99 counties. He did 350 community meetings. And everywhere he went people just said they liked Rick Santorum. … Conservatives were looking for someone to rally around, to coalesce around, to be the alternative to [Mitt] Romney, to beat Barack Obama. And I think tonight you're going to see that candidate is Senator Santorum.”

“I think there's going to be a surprise tonight. And I think that surprise is going to be: Santorum is actually going to win this in Iowa.”

Vander Plaats also suggested that Evangelicals were not likely to support Romney should he become the GOP presidential nominee.

“So far, throughout this cycle, he has pretty much dissed our base. Not shown us a whole lot of … you know, that he would want to come and visit us.” (The video is embedded in the right panel of this page. Visit our video library for more videos.)