Utah voters head to caucus sites across the state on Tuesday, where polls show the overwhelmingly Mormon electorate is expected to hand Republican front-runner Donald Trump a resounding defeat. Given Trump’s surprising success at courting evangelicals, some may be puzzled as to why Mormon voters—long thought to be a key component of the Religious Right—would reject Trump's charms. But for many Utahans, the businessman’s attacks on other religious groups, while popular with some, hedge uncomfortably close to the Mormon faith’s own troubled past.

Mormons—like modern-day Muslims—have a long history of being rejected by their fellow Americans because of their beliefs. Throughout the 19th century, followers of Joseph Smith were repeatedly expelled from lands by people who saw them as strange, foreign invaders, with some opponents even declaring them non-white. Angry, anti-Mormon mobs eventually murdered Smith during his short-lived campaign for president, and longstanding tensions between his flock and the U.S. government led to violent clashes and short-lived wars in pockets of the American West. So intense was the American rejection of Mormonism that the U.S. secretary of state once recommended that President Rutherford B. Hayes act to limit Mormon immigration into the country, a moment Utah Governor Gary Herbert saw as eerily reminiscent of Trump’s call to ban all Muslims from entering the United States last December.

“Utah exists today because foreign countries refused to grant the wishes of a misguided president and his secretary of state,” Herbert wrote in a Facebook post responding to Trump’s proposal. “I am the governor of a state that was settled by religious exiles who withstood persecution after persecution, including an extermination order from another state's governor. In Utah, the First Amendment still matters. That will not change so long as I remain governor.”

Trump, for his part, has tried harder to appeal to Mormon sensibilities since invoking his Muslim ban, launching a series of attacks on opponents that cast them as somehow un-Mormon. Last Friday, the Republican front-runner tweeted disparaging remarks about Senator Ted Cruz. Trump, who claims to be Presbyterian, said Cruz “should not be allowed to win” Tuesday’s Utah caucus because his views are out-of-step with the roughly 60 percent of the state’s population that identifies as Mormon.

“Mormons don't like LIARS!” Trump tweeted.

Hours later, Trump questioned the Mormon piety of Mitt Romney, the former Massachusetts governor and two-time GOP presidential candidate who also happens to be a devout member of the Church of Jesus Christ of Latter-day Saints (LDS). Romney, who won a whopping 93 percent of the vote in the 2012 Utah caucus, came out against Trump early March, calling him “a phony, a fraud.”

“Do I love the Mormons? I have many friends that live in Salt Lake City—and by the way, Mitt Romney is not one of them,” Trump told the crowd at a rally. “Are you sure he's a Mormon? Are we sure?”

Trump later claimed he was joking, insisting his point was that Mormons are “a very smart people” who should ignore Romney and back him in the Utah caucus, where 40 coveted delegates are at stake. But The Donald’s famously unshakable confidence—which has won him scores of evangelical Christian voters across the country—belies his consistently dismal support among Mormons. In fact, Mormon views of Trump are so toxic that he runs the risk of damaging the GOP’s longstanding lock on LDS members, who currently constitute the most reliably Republican religious group in the United States.

Trump, for instance, drew 11 percent support in the Beehive State in one recent poll—a distant third behind Senator Ted Cruz (53 percent) and Ohio Governor John Kasich (29 percent). And as BuzzFeed’s McKay Coppins points out, Trump has noticeably struggled to accrue Mormon votes throughout the 2016 election season, losing heavily Mormon counties during the primaries in Idaho and Wyoming—states where he placed second and third overall, respectively. In Oneida County in southeastern Idaho, where roughly 3 out of 4 voters are Mormon, Trump won just 17.8 percent of the vote, whereas Cruz walked away with 59.9 percent.

So what explains Mormon distaste for Trump? Some of it could be cultural, such as how Trump’s proclivity for insults and foul language contrasts sharply with the LDS church’s formal opposition to “any type of unclean or vulgar speech or behavior.” Some of it could be demographics; According to The New York Times, whites without high school diplomas are particularly likely to back Trump, but Mormons are significantly more likely than the general population to have at least some college-level schooling, with only 9 percent claiming less than a high-school education.

But anti-Trump sentiment among LDS members likely cuts deeper than curse words or educational achievement, and eventually circles back to acute disagreements over Trump’s notoriously hard-edged policy agenda—especially his inflammatory statements regarding undocumented immigrants. Trump continues to win praise—and votes—from his anti-immigrant base for proposing to deport all of 11.3 million immigrants in the United States, and drew cheers when he referred to people who travel across the U.S.-Mexico border as “rapists” and “criminals” during his speech announcing his campaign for president last year.

According to data from the Public Religion Research Institute, Mormons don't share Trump’s apparent disdain for migrants, with 45 percent saying that immigrants strengthen American society, compared to only 36 percent of Republicans who say the same. Utah Mormons in particular favor providing undocumented immigrants with a pathway to citizenship if they meet certain requirements, with 68 percent percent supporting the measure compared to 57 percent of Republicans generally.

And while Trump’s proposal to ban Syrian refugees and Muslims altogether from entering the country enjoys broad support among most GOP voters, repeated calls to exclude an entire religious group continue to trigger the exact opposite reaction in Mormon circles. When Trump announced his anti-Muslim proposal last year, the LDS Church issued a declaration implicitly condemning the idea—its first and only public statement regarding the 2016 election thus far.

“The Church of Jesus Christ of Latter-day Saints is neutral in regard to party politics and election campaigns,” the statement, which also included a quote from LDS founder Joseph Smith championing religious freedom, read. “However, it is not neutral in relation to religious freedom.”

Political leaders in the state have embraced that message. Utah’s Lieutenant Governor Spencer Cox didn’t mince words when discussing Trump’s attack on Mitt Romney’s faith, describing the former governor as “a great Mormon” and dismissing Trump’s comments as “[something I] never thought I would see a candidate for president do and say, especially someone in the Republican Party.” He also retweeted a message from Senator Orrin Hatch’s press secretary.

“Not sure how any Mormon could support Trump. As far as threats to religious liberty, Obamacare has NOTHING on him. #NeverTrump,” the tweet read.

Nominating Trump, it seems, could cost Republicans their longstanding support from Mormon voters: A Deseret News/KSL poll released over the weekend found that if he becomes the GOP nominee, many Utah voters plan either to stay home or switch parties, meaning the state could end up supporting a Democratic presidential candidate—either Hillary Clinton or Bernie Sanders—for the first time in more than 50 years. In the meantime, some are even calling on Mormons to be the driving force to deny Trump the GOP nomination.

Trump may be right that Mormons don’t like liars. But they also don’t like people who bash immigrants, or those who discriminate on the basis of religion.

And if the polls are any indication, they definitely don’t like Trump.