DES MOINES — The hearts of many evangelical voters, polls suggest, are with Ben Carson. But increasingly, their leaders’ heads are with Ted Cruz.

While the Texas senator trails the retired pediatric neurosurgeon by double digits in national surveys, prominent evangelical leaders and political operatives who work with the Christian conservative movement say it's the well-funded Cruz who has made the bigger organizational effort with politically active church goers.

He’s rounding up the very grass-roots leaders who wield influence with this crucial Republican voting bloc. And here in Iowa, where endorsements have often predicted caucus winners, that matters.

"Cruz has got a lot of people on the ground who can historically move numbers," said Bob Vander Plaats, a prominent and still unaligned conservative in Iowa who is hosting a major cattle-call for Republican presidential candidates on Friday night. Vander Plaats in previous cycles attached his endorsement to the candidate who ultimately won the Iowa caucuses, and this time, he is thought to be leaning toward Cruz.

Meanwhile, Carson, a newcomer to politics, is running an untraditional campaign in every sense — including in how he courts the religious faithful. Carson, who speaks particularly openly about his personal faith, approaches voters here with a heart-on-his sleeve style, but he hasn’t made engaging their political leaders a priority.

Tony Perkins, among the most influential evangelical leaders in the country, told CNN earlier this week of Carson: "He's not built relationships with conservative leaders. I don't know that he's actually looking for endorsements from conservative leaders. He may have a different approach to his campaign."

Perkins was on hand last week at a religious liberty rally in South Carolina organized by Cruz, who has now held two professionally produced events centered on the issue. The first, in Iowa in August, cast Cruz as the field's biggest defender of religious freedom. The senator, once a Supreme Court clerk, railed against the high court’s decisions on same-sex marriage and appeared onstage with people who have faced business problems over, for example, refusing to host a gay wedding. The second event allowed Cruz to make the same play for the religious and deeply conservative Upstate region of South Carolina.

And through both, Cruz has gained momentum within the evangelical community.

To capitalize, and build his list of supporters and donors, Cruz said Thursday that he is forming a “national prayer team.” Those who sign up will receive weekly emails that include prayer requests from Cruz and his wife as well as from the campaign team and other volunteers. Members will also be invited each Tuesday to pray together on 20-minute conference calls.

“We experience the power of prayer every day,” Cruz said in a statement, using religious language that resonates with evangelicals. “We’re organizing 'A Time for Prayer' to establish a direct line of communication between our campaign and the thousands of Americans who are lifting us up before the Lord.”

The next test of Cruz's organizational strength among Christian voters comes tonight, when the Republican presidential candidates converge on Des Moines for Vander Plaats's social issues-focused gathering.

That caps off a week in which Cruz locked down the endorsement of conservative Iowa congressman Steve King, and several months after winning over Steve Deace, a radio host well-regarded in Iowa evangelical circles. If Cruz gets Vander Plaats' nod, that would secure a trifecta of crucial Iowa Christian heavyweight endorsements for the Texas senator. Add to that the pastors he is tapping in all of Iowa’s 99 counties to recruit like-minded voters on his behalf, and Cruz is beginning to look like he has an organizational lock on this voting bloc, even if the polls say otherwise.

Indeed, according to the latest POLITICO Caucus released Friday, Republican insiders say it’s Cruz who is favored among evangelicals — by a mile.

“Cruz has got all the way from the networks of Steve Deace and now of Steve King as well, to a pastors’ network,” Vander Plaats said in an interview, as he named Cruz, Carson and Mike Huckabee the candidates who are most organized in the conservative world. He wouldn’t divulge who he favors.

Bobby Jindal, the governor of Louisiana, had also been competing hard for Vander Plaats's backing and was well-liked among the home-schooling crowd, but he dropped out this week, further clearing Cruz's path.

"I think all of the stars are beginning to line up now, a lot of people had been fighting in that space ... but I think there's a little bit of a 'shiny new car' element that applies to Cruz," said a plugged-in Iowa Republican who requested anonymity in order to speak freely. "Plus, I also think there's a penchant for wanting financial resources, [to see evidence that the candidate can] 'go the distance.' That will be the language you hear."

A central piece of Cruz's message, to religious leaders as well as to donors, is that he can last through the GOP primary, with more cash on hand than any other Republican and the deep organizational network in every state that votes through March 15, and is skilled enough to maneuver in Washington while keeping his distance from the GOP establishment. That is expected to be a factor in Vander Plaats’s decision.

Vander Plaats said that after he endorses, his message to evangelicals will be that it’s time to unite behind a single conservative candidate to face off against the mainstream GOP contender. King is already making that case for Cruz, and on Friday, he will help Cruz take the message to deeply conservative northwest Iowa, King's home base, as they jointly host two town halls.

“It’s probably too early, but I do think it’s on a lot of people’s minds — can we unite around a candidate?” Vander Plaats said. “People Friday night will leave the venue saying they could take any one of them … but the key is, we need to support one of them, so we can get that person over the finish line and so that our nominee can beat Hillary Clinton.”

It’s a goal widely shared throughout the conservative and evangelical movement. A group of movement leaders has been secretly meeting over the past year to interview candidates in the hope of coalescing behind a single contender. If that happens — and that’s far from certain — Cruz is well-positioned, perhaps best-positioned, to be the choice of many not only in Iowa but nationwide.

The Cruz campaign is actively trying to emerge as the conservative consensus pick. According to Cruz campaign manager Jeff Roe, the campaign has identified about 400 faith leaders whose support it wants and needs. More than 200 are now with Cruz, Roe said.

“It’s strong,” Roe said of Cruz’s support among evangelical voters and leaders. “And we believe between now and the first of the year, we’ll get [substantially] more. We’re hopeful. We work very hard, very [diligently]. We do the tactics of it, we do the strategy of it, we spend a lot of time focused on consolidating the conservative movement.”

Eric Woolson, a longtime Iowa operative who had worked on Scott Walker’s team, agrees that Cruz is in the lead with Christian conservative activists. Cruz, his campaign staff and his father, Pastor Rafael Cruz, have been putting intense emphasis on courting religious Christian leaders in the state for months, and it shows, Woolson said.

“There were folks in the evangelical community I spoke to over the summer who were talking about how impressed they were with Sen. Cruz’s dad and how much work he’d done, and then, of course, meeting Sen. Cruz, they were very impressed with him,” said Woolson, who is now not attached to any GOP candidate. “They have worked that segment of the caucus vote very smartly, very wisely, and I think they’re in very good shape.”

Not that things have always gone smoothly. When Cruz went to Kentucky to show solidarity with Kim Davis, a county clerk who refused to issue a marriage license to a gay couple and was briefly jailed, he was badly overshadowed by Huckabee, the 2008 winner of the Iowa caucuses who also has a strong pastors' network, and managed to crowd Cruz out of the spotlight at a rally for Davis. (It turned out that a Huckabee staffer physically boxed Cruz out.)

And Cruz continues to lag Carson, who raised more money than anyone in the Republican field last quarter and draws huge crowds of the Christian faithful. The Cruz campaign has no appetite for drawing contrasts with Carson, who has sky-high favorability ratings among Republican voters.

But Huckabee has so far failed to gain traction in the polls, and Carson is already showing signs of faltering as his foreign policy positions in this post-Paris political climate are scrutinized.

All of that plays into Cruz’s pitch that he is the most durable conservative in the race.

Marjorie Dannenfelser, the head of the anti-abortion Susan B. Anthony List who does not plan to endorse, said that while Carson’s openness about, and comfort with, his faith, has moved her organization’s members, it is Cruz who appears to have made among the biggest attempts so far to court leaders on the national level.

She chalks up much of his lagging in the polls to a lack of name ID compared with Carson, who is a best-selling author and motivational speaker and was well-known among conservative Christians before he launched a presidential bid. The Cruz campaign went on television in Iowa this week in an effort to correct for that deficit.

“Carson is a believer, he’s very compelling, he attracts leaders everywhere he goes, but a lot of this [for Cruz] is playing catch-up,” she said. “Cruz has definitely got it. He’s got that particular spiritually attractive charisma that you need if you’re going to recruit the spiritually engaged.”