Though his family hails from Michigan and he is governor of Massachusetts, the lion's share of contributions to likely Republican presidential candidate Mitt Romney come from Utah. This is hardly surprising. More than 70% of Utah's residents are, like Mr. Romney, members of the Church of Jesus Christ of Latter-day Saints (LDS). As fellow Mormons, they feel a special kinship with him. Some even see in him the potential to fulfill a 160-year-old premonition by Mormon founder Joseph Smith, known as the "White Horse Prophecy."

In 1843, according to followers of Smith, he predicted that one day American citizens would be denied their most basic rights and the U.S. Constitution would "hang like a thread as fine as a silk fiber." "A terrible revolution will take place in the land of America, such as has never been seen before; for the land will be left without a Supreme Government, and every specie of wickedness will be practiced rampantly in the land," Smith reportedly said.

It would then be up to the Mormon people, symbolized by a white horse, to ride in and save the republic from collapsing. "I love the Constitution; it was made by the inspiration of God, and it will be preserved and saved by the efforts of the White Horse," Smith purportedly told his followers, borrowing the white horse image from the apostle John in the Book of Revelation.

Susan Easton Black, professor of church history and doctrine at Brigham Young University in Provo, Utah, said the White Horse tale was originally publicized by two devout Mormon men seeking to make money off of the prophet's narrative. According to Mrs. Black, the men sold the prophecy in a pamphlet to early Utah pioneers.

The prophecy, in various forms, was recounted in contemporaneous personal journals and spread by word-of-mouth among Latter-day Saints in early settlements in Illinois and then Utah. Later tellings of the story escalated its drama, painting pictures of a single Mormon man rushing in like a white knight in shining armor at a time of constitutional crisis.

Church prophets after Smith--who himself ran for president in 1844--toned down the prophecy somewhat, rejecting the white horse imagery but embracing the concept of the Constitution as a divinely inspired document that will face malicious attacks from unspecified enemies. And today students and teachers in LDS Sunday school classes across the country commonly discuss the idea that the Constitution is under attack.

"What do I think about it? Someday it will come true," says Jeff Hartley, executive director of the Utah Republican Party. "There have been several Republicans that I have known who thought that they were that individual," says Mr. Hartley, citing Todd Nielson, a GOP congressional candidate who failed in the 1996 state primary and Republican LaVar Christensen, currently vying for a seat for Utah's Second Congressional District. They have intimated to him that "the Constitution's hanging by a thread, and that they would be there to defend the Constitution," says Mr. Hartley. "We believe in personal revelation, so it's hard to dispute or question someone who feels like they were inspired to run for office."

The prophecy was discussed during Utah Sen. Orrin Hatch's 2000 bid for the Oval Office--especially after the senator used the phrase "hanging by a thread" during a radio interview. Mr. Hatch denied that his use of the phrase was a veiled reference to the prophecy.

Still, the prophecy continues to inspire Mormons to run for office, on both sides of the aisle. Steve Olsen, the Democratic candidate for Utah's First Congressional District, told me that Smith's vision inspired him to run. According to Mr. Olsen, a party official persuaded him to throw his hat into the ring by alluding to the prophecy. "You owe it to the Lord and the people to run," Mr. Olsen was told by Larry Daniel, chairman of the Iron County (Utah) Democrats. When Mr. Daniel noted that "our Constitution is more under attack by the Republicans than by outside forces and you are one of the elders of Israel who can help save it," Mr. Olsen says he was moved. (Mr. Olsen says that both he and Mr. Daniel are concerned about what they see as the expansion of executive power beyond constitutional bounds.)

But the bottom line, according to Mrs. Black, is that the prophecy as a whole is false. She doesn't talk about it in her classes: "We have more important things to discuss that are true." Indeed, LDS Church spokesman Mike Otterson is quick to point out the prophecy is not official canon. He says, "There may be some members of the church who think that in supporting a Mormon candidate and seeing the possibility of a Mormon president, there may be some sort of scriptural validation." But Mr. Otterson explains, "It begins to take on almost a zealous tone that I find a little worrisome."

As Mr. Romney continues rising among 2008 hopefuls, questions about the prophecy will continue to surface: Would Mormons see a Romney White House as a White Horse? "I have no idea," says Utah Republicans' Mr. Hartley. "And frankly, I would worry about anybody who thought they were fulfilling prophecy because the way I understand it, you don't seek after those things. You don't recognize it until it's probably already happened."