DES MOINES, Iowa – Conservative evangelicals on Sunday showed signs of coalescing behind former Pennsylvania senator Rick Santorum – raising the possibility of a surprise finish in caucuses that will mark the formal start of the 2012 GOP race for president.

A surge by yet another conservative champion in a chaotic field could be good news for frontrunner Mitt Romney, but bad news for former Georgia congressman Newt Gingrich, who – after attending church services here – continued to push himself as the former Massachusetts governor’s most potent nemesis.

The former U.S. House speaker, who has been hammered by a relentless barrage of TV ads funded by a Romney-affiliated political action committee, accused Romney of using his substantial campaign treasury to dictate Tuesday’s outcome in Iowa.

"You figure out between 2007 and 2008 and 2011 and 2012 how many dollars per vote Romney has spent, and it will rival [New York City Mayor Michael] Bloomberg," Gingrich told reporters after leaving Saint Ambrose Cathedral. "Romney would buy the election if he could," said Gingrich who has sworn to maintain a positive campaign.

A final poll by the Des Moines Register, published Sunday, found Romney with 24 percent support among likely voters in Iowa while Texas congressman Ron Paul had 22 percent. Santorum – previously confined to single digits -- placed third with 15 percent, followed by Gingrich, with 12 percent, and Texas Gov. Rick Perry, with 11 percent. Michele Bachmann, the congresswoman from Minnesota, had just 7 percent support.

In 2008, conservative evangelicals in Iowa were responsible for pushing former Arkansas governor Mike Huckabee to victory there. Sunday’s poll showed religious conservatives still splintered among several candidates – but Santorum’s rapid rise indicates the situation could be changing.

Forty-one percent of those surveyed said they could still be persuaded to support another candidate.

The emphasis on evangelical voters could be seen in a final TV ad broadcast by Perry emphasizing his religious commitment. “I’m not ashamed to talk about my faith,” he says time and again to Iowa voters. While Gingrich has drawn 30 or so volunteers from Georgia for his final push, Perry has summoned several hundred volunteers from Texas.

Bob Vander Plaats, president of The Family Leader, an Iowan Christian group, whose support was crucial to Huckabee four years ago, last month attempted to persuade Bachmann to exit the race – and make it easier for religious conservatives to rally behind a single candidate. Vander Plaats now appears in a Santorum TV ad – and says an outright victory for the former Pennsylvania senator is within reach.

“It’s going to make Huckabee’s win in 2008 not so surprising anymore,” Vander Plaats predicted.

A substantial shift of conservative Christians to Santorum would undercut Gingrich in Iowa, and ensure a splintered opposition to Romney in New Hampshire – where Santorum on Sunday vowed to carry the fight.

The failure of evangelicals to rally to his side would also be something of a rebuke to the thrice-married Gingrich, who has spent the last several years improving his ties to religious conservatives. In 2009, Gingrich converted to Catholicism, the religion of his third wife, Callista. In several forums throughout the campaign, he has confessed his personal failures – which include affairs during his first two marriages.

“Not endorsing Newt was very tough for me,” said Vander Plaats. “I’m a big fan of Newt, and he and I are very close.”

Vander Plaats doesn’t doubt that Gingrich is a changed man.  “This is not a road-to-Des Moines conversion for Newt.” The problem, the Christian activist said, is that the barrage of negative ads has revived concerns about Gingrich’s more secular baggage from a 40-year political career -- such as his work for Freddie Mac, and his association with then House Speaker Nancy Pelosi in a TV commercial touting the reality of climate change.

“I think that people just got cautious about – if this becomes a debate about Newt and his past rather than about [President Barack] Obama and the economy, I think they don’t think they can win that,” Vander Plaats said.

Sunday’s poll by the Register provided backing for Vander Plaats argument. Of those Republicans and independents surveyed, 41 percent – a strong plurality -- declared Gingrich to be the “most knowledgeable” candidate in the Republican field. But the same voters also declared him to the be the “most ego-driven” and least dedicated to limiting the influence of government.

Gingrich said Sunday he’ll continue to make his case to conservative Christians. “I am the only candidate in the race who actually has helped significantly change Washington twice, in the 1980s with [President Ronald] Reagan and in the 1990s as [House] speaker. I think most evangelicals want to actually change Washington, not just have somebody preside over the decay. That is my primary argument,” he said to reporters as he left church.

A few hours later, Gingrich was wading through a crush of supporters at the West Towne Pub in Ames – just north of Des Moines -- shaking hands and posing for pictures before ending his tour in the "Beer Cave," a television-choked seating area packed with even more fans.

College students in the crowd squealed as he and Callista drew near.

Several probable caucus- goers in the crowd said they liked Gingrich, but remained undecided about who they would pick on Tuesday. Joanne Duncalf, a health insurance saleswoman from Clarion, said she is split between Gingrich, Perry and Santorum. She said she likes Santorum’s family values and believes he will carry most of the evangelical vote Tuesday.

A Catholic, she said it is important for her chosen candidate to be church-going. She predicted Gingrich will place third Tuesday. Democrats, she said, “don’t want to have Obama have to debate him. He is too intelligent for him.”