Employees listen to Republican presidential candidate Mitt Romney during a campaign stop at Giese Manufacturing on Nov. 7 in Dubuque, Iowa. (Charlie Neibergall/AP)

The biggest barrier between Mitt Romney and the Republican presidential nomination may be an informal coalition of pastors and evangelical leaders in the key state of Iowa, some of whom have long been skeptical of his conservative credentials or are quietly uncomfortable with his Mormonism.

Romney’s limited ability to attract support among evangelical voters hurt him in his 2008 campaign and is one of the reasons he remains vulnerable in early-voting states such as Iowa and South Carolina.

In late 2007 and early 2008, David Lane, a conservative Christian activist based in California, helped put together a series of private events for evangelical pastors in Iowa and other early-voting states that were billed as public policy forums; they usually also included one presidential candidate, former Arkansas governor Mike Huckabee.

At the same time, Bob Vander Plaats, a longtime social conservative activist here, tapped into his own network of pastors and evangelicals as Huckabee’s Iowa campaign chairman.

Aided by the endorsements of many influential pastors, Huckabee went on to win the Iowa caucuses with huge support from evangelical Christians, dealing Romney’s 2008 candidacy a blow from which it never recovered.

This time, Lane and Vander Plaats are both emblematic and symptomatic of Romney’s problems.

Neither is formally aligned with any of the 2012 candidates, but both are making moves to create another groundswell of evangelical voters in Iowa that could again threaten Romney’s effort.

“Eighty to 90 percent of this constituency will not vote for Romney,” Lane said.

Family Leader forum

On Saturday, Vander Plaats will host a forum here with candidates to highlight abortion and other moral-values issues. Romney will not be present. Lane has again been hosting the private pastor events in key primary states, and next month he is helping to organize a public prayer and fasting event in Cedar Rapids. He says all of the GOP candidates will be invited.

More than likely, Romney will not be present, given what Lane has said about Romney’s religion.

The Lane event is modeled on “The Response,” the Christian rally in Houston that Lane helped organize in August. Texas Gov. Rick Perry was the featured speaker.

Vander Plaats now runs a social conservative group called the Family Leader, which will host the Saturday event, and says an endorsement could follow. Such an endorsement could make a critical difference for the candidate who gets it.

All the leading Republican candidates are scheduled to attend Saturday’s event except for former Utah governor Jon Huntsman Jr., who has effectively written off Iowa, and Romney. Romney aides did not say why he is not attending the forum but noted that he has attended numerous other conservative gatherings.

Evangelical Christians made up more than half of all the voters in the 2008 Iowa caucuses and will probably be the decisive voting bloc again in 2012. If the 2008 scenario repeats itself, the coalition of pastors and other influential Christian conservatives led by people like Vander Plaats and Lane would have enormous influence in deciding which candidate has the chance to stitch together a win out of the anti-Romney sentiment among evangelicals. Vander Plaats does not think it will take that much to win, arguing that it is possible to win the caucuses with much less than a majority of voters.

“If there’s a coalescing, they only need 30 to 35 percent” to win, he said.

But Vander Plaats, who says that neither he nor his group is anti-Romney, noted that Romney could win if evangelicals do not come to some consensus about an alternative.

“They could divide that up and Romney walks out of that with a victory,” he said.

Marvin Olasky, editor of the evangelical World magazine, noted that on key issues such as abortion and gay marriage “all of the candidates are within the frame” for evangelical Christians.

“It may not be that a single candidate can get that vote,” said Ed Rollins, who managed Huckabee’s 2008 run.

Antipathy for Romney

While Lane says he has invited all of the candidates to speak at his pastors sessions during the campaign, Republican operatives privately say he is trying to steer the pastors toward Newt Gingrich or Perry, both of whom have long ties to Lane.

There is little question about his antipathy toward Romney, however.

In an e-mail exchange this year obtained by the Daily Beast, Lane, a one-time aide to the Rev. Jerry Falwell, praised Robert Jeffress, the Dallas pastor who introduced Perry at an event in October and later said that Mormonism is a cult.

“Getting out Dr. Jeffress message, juxtaposing traditional Christianity to the false god of Mormonism, is very important in the larger scheme of things,” Lane said in the e-mail exchange.

Lane confirmed in an interview that he wrote the e-mail but said his concerns about Romney were about past liberal stands on key issues.

But in interviews, some social conservatives in Iowa are blunt about their resistance to Romney.

“I’m reluctant to support any candidate who does not believe the Bible is the inspired word of God,” said Cary Gordon, a Sioux City pastor who has not yet endorsed a Republican candidate. He said the existence of the Book of Mormon illustrates that Mormons do not believe in the Bible as he does.

Lane predicted that even if Romney wins Iowa, another candidate would probably challenge him in South Carolina.

“If somebody will start speaking to this constituency, evangelicals will decide who wins in Iowa and South Carolina and who’s going to be the nominee,” he said. He added, “The candidate who sounds the trumpet will derive the benefit.”