Republican presidential candidate Donald Trump Donald John TrumpBarr criticizes DOJ in speech declaring all agency power 'is invested in the attorney general' Military leaders asked about using heat ray on protesters outside White House: report Powell warns failure to reach COVID-19 deal could 'scar and damage' economy MORE is calling rival Ted Cruz Rafael (Ted) Edward CruzLoeffler calls for hearing in wake of Netflix's 'Cuties' Health care in the crosshairs with new Trump Supreme Court list 'Parks and Rec' cast members hosting special reunion to raise money for Wisconsin Democrats MORE "dirty" for starting a rumor about Ben Carson Benjamin (Ben) Solomon CarsonBiden cannot keep letting Trump set the agenda The Hill's 12:30 Report: Trump heads to New Hampshire after renomination speech Five takeaways on GOP's norm-breaking convention MORE's campaign ending after the Iowa caucuses.

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"[Ted Cruz] insulted Ben Carson," the billionaire said at a news conference before a campaign rally in Milford, N.H. "What he did to Ben Carson was a disgrace."

Trump also accused Cruz of insulting the people of Iowa when he sent out a voter violation mailer before the caucuses.

When asked if he thought Cruz was running a dirty campaign, Trump responded that his rival "certainly was dirty."

"What he did to Ben Carson was terrible," Trump said. "When they said Ben Carson is out of the race and come vote for him, I thought it was terrible."

Cruz apologized to Carson earlier Tuesday for the "mistake."