Call it the Mormon Firewall.

A new poll suggests Ted Cruz has built an enormous lead in Utah, buoyed by Mitt Romney’s endorsement and a Mormon population that resists Trump’s bullying appeal. If Cruz can win an outright majority in Utah, he may be able to stop the seemingly inexorable rise of the reality TV star.

The new survey by Y2 Analytics shows Cruz with 53 percent support among likely Republican caucus-goes. If that matches up with Tuesday’s caucus results, Cruz will win all of Utah’s 40 GOP delegates. (If any candidate reaches a clear majority of the caucus, majority-take-all is triggered.)

Ohio Gov. John Kasich comes in second with 29 percent, while Trump was a distant third at 11 percent.

The battle for the Republican nomination and the fight to stop Trump rests heavily with the Western states now. Cruz’s chance to hit the majority in Utah is his best hope to stay in the fight, as Trump is polling 14 points ahead of Cruz in Arizona, which is winner-take-all. Arizona awards 58 delegates to the winner of the primary vote on Tuesday. While Trump’s lead there is considerable, it isn’t insurmountable since Cruz has frequently outperformed the polls in other state primaries, in some cases by double digit margins.

Meanwhile, the Trump campaign has written off Utah, admitting that it’s not “a place where we are expected to perform exceptionally well.”