Rick Santorum’s presidential campaign has started to show signs of life, and GOP kingmakers in Iowa say the former senator has an outside shot of winning the caucus next month. 

While the large religious conservative voting bloc remains split between Santorum, Michele Bachmann and Rick Perry, many experts in the state say Santorum has more structure and momentum than the other two and could coalesce enough support to win the state.

However, he’s failed to break through in polling, barely making it out of the single digits. And if evangelical Christian voters, who make up the majority of caucus voters, remain divided, that could hand another contender the victory.

{mosads}But Santorum got a powerful boost on Tuesday with an endorsement by Bob Vander Plaats, one of Iowa’s most powerful social conservatives. 

The former Pennsylvania senator has spent more time in the state than any other candidate, is closely aligned ideologically with the state’s large number of religious conservatives, and has rolled out a number of endorsements from local Republican activists in recent days.

A strong showing by Santorum would echo former Arkansas Gov. Mike Huckabee’s (R) late come-from-behind victory in Iowa. Huckabee’s move to the top came shortly after Thanksgiving, while Santorum has not yet shown that surge. But some say it’s not too late.

“The guy on the move is Santorum. He’s shown movement in terms of lining up these endorsements and people who can move voters, and showing movement on the ground,” said Craig Robinson, a former political director of the Iowa Republican Party, who is not endorsing a candidate. “He’s got major endorsements rolling in, he’s got his super-PAC advertising, he’s got his own TV ad up. His campaign is starting to show that there’s indisputable proof that there’s momentum. … Bachmann and Perry are showing activity and calling it momentum.”

Santorum has slowly but steadily risen in the polls, unlike Bachmann, Perry, Herman Cain and Newt Gingrich, all of whom soared before sputtering. He was in a three-way tie for fourth place with Perry and Bachmann at 10 percent in the latest poll from the Democratic firm Public Policy Polling, just four points behind Gingrich.

Ron Paul and Mitt Romney have led recent polls, but most observers in Iowa say the two have hard ceilings of support and are unlikely to be able to expand much on their current bases of about 20 percent of the vote, leaving any candidate who can catch a late spark within striking distance. 

Rep. Steve King (R-Iowa), a conservative kingmaker in the state, predicted that a large number of social conservatives would remain swayable up through the election, and campaign infrastructure would make the difference. King, who has not endorsed but is close with Bachmann, said that Santorum and Bachmann would benefit from that.

“The support is going to flow on caucus night to the candidate or candidates who are best organized on the precinct level,” he said. “Whoever can deploy a couple thousand good speakers out there to each one of those places who are compelling can make a difference because there will be a lot of undecideds sitting out there. At this point it looks to me like Santorum has the best structure and Bachmann is closing on that right now. Those two structures are the two best in the state.”

Vander Plaats heaped praise on Santorum’s record on Tuesday, and on Saturday called Bachmann and asked that she drop out of the race (she refused). He is popular with Iowa’s conservatives, led the successful fight to remove three Iowa Supreme Court justices after they legalized gay marriage, and ran for governor in 2010, nearly winning the GOP primary against popular Gov. Terry Branstad (R). 

He received nearly 100,000 votes in that race, almost as many voters as usually turn out for the GOP presidential caucuses.

“It’s a meaningful endorsement and one which I’m sure Michele Bachmann wished she could have received,” said Danny Carroll, a social conservative activist and Bachmann supporter in the state. “It would be a mistake to write Rick Santorum off; it would be inaccurate. You can’t have the kind of support and endorsements Sen. Santorum has received and not be a serious competitor.”