As Mike Huckabee sat on an upholstered chair at a suburban megachurch Sunday morning, he heard the biblical message about running the race of life and persevering in the face of all challenges.

Heading for his car after the service ended, the former Arkansas governor and onetime Baptist preacher said he had "prayed for strength for the weak."

Five days before the Iowa caucuses, Huckabee could have easily been referring to his presidential candidacy, once the longest of long shots but now on the verge of an improbable upset in the first state in the contest.

Even as the Democratic race in Iowa has become tied in a three-way knot, the Republican race has settled into a head-to-head battle pitting Huckabee against former Massachusetts Gov. Mitt Romney.

Romney, for months the presumptive front-runner in Iowa, has vastly out-spent and out-organized Huckabee, only to see his lead evaporate. Huckabee has held the lead for a month, although polls this weekend showed that the race may be tightening again.

Religion -- Huckabee's, Romney's and Iowa's Republicans' -- is the key to understanding the dynamic fueling the race between the two candidates.

Huckabee has been fervently unabashed in his embrace of evangelical Christianity, a set of beliefs embraced by as many as 40 percent of the people who are likely to turn out for the GOP caucuses Thursday night.

Despite his lack of organizational muscle throughout the state, he has tapped into the grass-roots networks of home-schoolers and evangelicals in the hopes of motivating them to caucus.

"We haven't been political before, but we're trying to get there," said Deanna Berry, an Indianola resident and longtime member of the Cornerstone Family Church, where Huckabee worshiped Sunday. "This time, we have to get the Christians out and vote because they really haven't before. And I like Huckabee -- he's saying things the nation needs to hear."

During the service, the Rev. Dan Berry told several hundred parishioners they should caucus this week because "we, as children of God, need to participate in this process. I know you're sometimes discouraged, but we need to give voice to things that are important to us."

Among those, he said, was pushing the Democrats and Republicans to endorse a statement condemning same-sex marriage.

Berry said he was delivering a nonpartisan message, handing worshipers information on both parties' caucus plans. As for Huckabee's appearance, in which he didn't speak, "he just wanted to worship with us today," Berry said.

Romney's Mormon beliefs are something of a wild card in the race because some evangelicals regard his religion as little more than a cult. Even so, the most recent polls showed that he has regained ground among those voters and on Saturday he snagged the endorsement of the chairman of the influential Iowa Christian Alliance.

The race between Romney and Huckabee has become increasingly nasty in the past several days. As Huckabee has stumbled over a series of foreign policy issues, Romney has broadcast ads blasting Huckabee for inexperience.

And much as Romney has been microscopically examined because of his religion, Huckabee has been experiencing the same treatment. During an appearance Sunday morning on NBC's "Meet the Press," he was grilled about his beliefs, saying at one point, that as governor, "I didn't replace the Capitol dome with a church steeple."

After his TV appearance, Huckabee swung back -- hard -- at his rival. "If a person is dishonest in order to get a job, do you believe that he will be honest if he gets the job?" he asked. "I want my people to know these attacks shouldn't shake their confidence because it hasn't shaken mine."

Even when he's not physically in a church, Huckabee's campaign rallies more resemble revivals than intimate meet-and-greets favored by other candidates.

A few nights ago, more than 1,000 of his supporters jammed a hotel ballroom and heard an hour's worth of both red-white-and-blue and overtly religious testimonials from warmup speakers.

"Here's a man who's cut taxes by a biblical approach," said former South Carolina Gov. David Beasley. "He's not a Washington politician, but I'm fed up with Washington politicians and I think most of you are, too."

When Huckabee took the stage, he told the crowd what they wanted to hear about the need for lower taxes and toughened immigration enforcement, but leavened it was an aw-shucks spin on his religion.

Noting that everyone in the room was a believer, he cracked, "will the ushers now please pass the plate?" And he offered a rewrite of the Beatitudes of Jesus: "Blessed are the brief, for they shall be invited to speak again."

Bob von Sternberg • 612-518-3182