The Donald isn't taking lightly Sheena Monnin's claim that a contestant knew the names of the finalists before the Miss USA show was broadcast.
Trump, who runs the Miss Universe Organization, says they'll sue the 27 year old.
"She made a very false charge and she knows it's a false charge," Trump told Good Morning America this morning.
In a statement to E! News, the Miss Universe Organization reported that Monnin cited its policy regarding transgender contestants as the reason for her resignation.
"Today she has changed her story by publicly making false accusations claiming that the pageant was fixed, however the contestant she privately sourced as her reference has vehemently refuted her most recent claim," organizers say.
E! reports Monnin had publicly called the organization "fraudulent, lacking in morals, inconsistent and in many ways trashy."
Two months ago, the Miss Universe Organization, which runs the Miss USA pageant, overturned its initial decision to bar Miss Canada Jenna Talackova from competing in the beauty contest.
On GMA today, The Donald went against what pageant officials claim was her motivation for resigning by downplaying the transgender controversy.
"I don't think that she had an issue with that," he said. "I think her primary issue is that she lost and she's angry about losing, and frankly, in my opinion, I saw her barely a second and she didn't deserve to be in the top 15."
Pageant officials also bring up the "sore loser" aspect of the controversy.
"We are disappointed that she would attempt to steal the spotlight from Olivia Culpo of Rhode Island on her well-deserved Miss USA win," officials told E!.
Culpo gained support in and out of LGBT circles thanks to her response to the toughest question of Sunday night's pageant: "Would it be fair if a transgender woman won the Miss USA title over a natural-born woman?"
"I do think it would be fair," she answered, acknowledging that, while some people might "be a little apprehensive to take that road," there are so many people "who have a need to change for a happier life. I do accept that because I believe it's a free country."