Donald TrumpDonald John TrumpTrump watching 'very closely' as Portland braces for dueling protests WaPo calls Trump admin 'another threat' to endangered species Are Democrats turning Trump-like? MORE lashed out at former GOP presidential nominee Mitt Romney and questioned his religion in a campaign rally in Mormon-heavy Utah.

"Do I love the Mormons? OK, I love the Mormons," Trump said to cheers. 

"By the way, Mitt Romney is not one of them ... Are you sure he's a Mormon? Are we sure?"

Trump and Romney have been in a heated feud – Romney has been outspoken in his opposition to Trump as the party's nominee. Earlier Friday, Romney announced that he would be voting for Ted CruzRafael (Ted) Edward CruzTrump moves forward with F-16 sale to Taiwan opposed by China The Hill's Campaign Report: Battle for Senate begins to take shape O'Rourke says he will not 'in any scenario' run for Senate MORE in Utah because he's the best chance to keep Trump from winning there Tuesday, even though he has previously supported John Kasich. 

Trump, who has claimed a surprising portion of the Evangelical vote, has made a play for Mormon voters as the Utah caucuses approach.  

Trump's rally in Salt Lake City is his first since a big primary day on Tuesday, where he won four states and is slightly ahead of Cruz in Missouri, which has yet to make a final call on results.