Ben Carson was incensed as the results of Monday night’s Iowa caucuses rolled in, accusing the winner of spreading falsehoods about him at caucus sites.

Carson’s team claimed that Ted Cruz’s campaign deliberately sent emails to supporters to spread false rumors at caucus sites that Carson had dropped out, so his supporters would caucus for other candidates. And after initially denying any wrongdoing late Monday, Cruz apologized Tuesday and called it a “mistake.”

“That is really quite a dirty trick,” Carson told reporters Monday evening. “That’s the very kind of thing that irritated me enough to get into this quagmire.”

Get our Politics Newsletter. The headlines out of Washington never seem to slow. Subscribe to The D.C. Brief to make sense of what matters most. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

“To have campaigns come out and send emails to their caucus speakers suggesting that Dr. Carson was doing anything but moving forward after tonight is the lowest of low in American politics,” said Carson campaign manager Ed Brookover.

“This is horsesh-t,” Rob Taylor, Iowa state representative and Carson’s Iowa co-chair, said simply.

Iowa Caucus results 2016

“Last night when our political team saw the CNN post saying that Dr. Carson was not carrying on to New Hampshire and South Carolina, our campaign updated grassroots leaders just as we would with any breaking news story,” Cruz told CNN in a statement Tuesday. “That’s fair game. What the team then should have done was send around the follow-up statement from the Carson campaign clarifying that he was indeed staying in the race when that came out.”

Members of Carson’s team furnished evidence Monday of various precinct captains alleging misconduct by the Cruz campaign.

Ryan Rhodes, Carson’s Iowa state director, showed reporters a text on his phone from Barbara Heki, a Mike Huckabee supporter. “The Cruz speakers at our caucus announced Carson was suspending his campaign for a while after caucus. They did this before the vote. Same thing happened at another caucus. Sounds like slimy Cruzing to me,” the text read.

Jason Osborne, Carson’s deputy senior strategist, read aloud another missive, this one an email from their precinct chair in Muscatine: “The guy speaking for Ted Cruz right before the vote, he was supposed to be done, he announced that there was a story on CNN that Ben Carson was taking a break after Iowa, and then stated, ‘So you might want to rethink wasting your vote on him.’”

Cruz’s team flatly denies the allegations. “That’s absurd,” spokesperson Catherine Frazier said.

— With additional reporting by Alex Altman

Write to Tessa Berenson at tessa.berenson@time.com.