The people who seem most interested are the ones who fear Romney would be a puppet of Mormon church leaders if he were elected.

Romney has sought to win over evangelical Christians by emphasizing common ground.

"I believe Jesus Christ is my savior. I believe in the Bible. I believe that liberty is a gift of God and not of government," Romney said last month. "I believe in serving other people, that it's part of a religious heritage."

As Massachusetts governor, Romney was not seen as being under the church's control. And official Mormon policy is to stay politically neutral and not endorse candidates.

But some stalwart Republican voters remain dubious.

Rocky Hulse, who runs the Christian Visitors Center with his wife, has written a book, "When Salt Lake City Calls," making the case that a Mormon president would have to put the church's needs ahead of the country's.

"This man's allegiance, first and foremost, is to what he has sworn in the temple," Hulse said.

In the 1840s, Nauvoo was home to thousands of Mormons who were brought there by Joseph Smith. That made it one of the largest cities in the west, not far behind Chicago. Operating under a state charter that gave them broad powers of self-governance, Mormons had their own militia, their own courts and enough votes to tip state elections.

The church's power — and Smith's willingness to use it — angered non-Mormons in the area. When Smith destroyed a newspaper that had criticized him, he was brought up on legal charges. While he was being held in a nearby town, a mob of 200 men stormed the jail and shot Smith and his brother to death.

Soon after, the Mormons began migrating west. Nauvoo dwindled and was just another dying river town until Mormon tourism took off. The new temple's opening in 2002 cemented Nauvoo's status as a major destination for Mormons.

The temple sits atop a bluff, gleaming in the sun. It can be seen for miles across the flat Iowa farmland of Lee County, which lies about 130 miles southeast of Des Moines.

Patrick Breen, the Iowa county's Republican chairman, said he hasn't seen any evidence that Romney's religion is costing him votes in the area. Romney is being received as warmly as the rest of the GOP field, he said.

But there are exceptions.

In the little Iowa town of Montrose, which was once a Mormon settlement and has streets aligned to offer a perfect view of the Nauvoo temple, Nikki Edwards said she was raised a Mormon but has since left the church.

"I don't agree with the religion," she said, "and I don't want to follow a president with those beliefs."