Donald Trump is so confident about the loyalty of his supporters that he predicted they would stick with him even if he shot someone.
The Republican presidential frontrunner was speaking at a rally nine days before the Iowa caucuses open voting in the 2016 campaign.
He told an enthusiastic audience at a Christian school, Dordt College: “I could stand in the middle of Fifth Avenue and shoot somebody, and I wouldn’t lose any voters, OK? It’s like incredible.”
The tycoon attacked conservative commentator Glenn Beck’s support of rival Ted Cruz and welcomed a figure from the Republican establishment, Senator Chuck Grassley of Iowa.
Mr Beck campaigned for Mr Cruz and held little back in going after Mr Trump.
“The time for silliness and reality show tactics has passed,” he said, and warned a Trump victory in the February 1 caucuses could have lasting consequences.
“If Donald Trump wins, it’s going to be a snowball to hell,” he said.
Mr Trump called Mr Beck a “loser” and a “sad sack”.
He demonstrated the extent to which some in the Republican establishment have begun to accept a potential Trump nomination when Mr Grassley introduced him at an event.
The senator did not offer an endorsement, but his presence underscored Mr Trump’s enduring position at the top of the polls as voting approaches.
Mr Cruz, running close with Mr Trump in Iowa polls, was almost entirely focused on the billionaire in his Ankeny event.
He professed core conservative values and drew a sharp contrast with Mr Trump on issue after issue, without using his name.
He claimed one Republican candidate “for over 60 years of his life” supported so-called partial-birth abortion and a “Bernie Sanders-style socialised medicine for all”.
Mr Trump is 69 and unlikely to have had positions on abortion and health care as a child.
Mr Sanders, a liberal senator, is mounting a strong challenge to former Secretary of State Hillary Clinton in the race for the Democratic presidential nomination.
Mr Cruz blasted Mr Trump’s past reluctance to strip money from Planned Parenthood and cast the billionaire’s plan to deport more than 11 million people who are in country illegally as “amnesty” because he would then let many of them return.
But Mr Cruz shrugged off Trump’s shooting comment: “I will let Donald speak for himself. I can say I have no intention of shooting anybody in this campaign.”
He added that he would keep his criticism focused on issues: “I don’t intend to go into the gutter.”