A posting on Miss Pennsylvania Sheena Monnin's Facebook page claims another contestant learned the names of the top 5 finishers on Sunday morning – hours before the show was broadcast.
Monnin claims the other contestant told her the names of the top 5 she spotted on a planning sheet for the telecast – and she decided to step down as soon as those same contestants were named during the show.
"In my heart I believe in honesty, fair play, a fair opportunity, and high moral integrity, none of which in my opinion are part of this pageant system any longer," Monnin wrote in one of her Facebook posts.
Monnin, of Cranberry, Butler County, did not immediately respond to a Facebook message from The Associated Press.
Donald Trump, who runs the Miss Universe Organization, called Monnin's claims that the pageant was fixed "totally ridiculous" in a live interview Wednesday on ABC's "Good Morning America" and said the pageant organization plans to sue Monnin for making the "false charge."
"We're going to be suing her now. She made a very false charge and she knows it's a false charge," Trump said.
Pageant organizers confirmed Monnin resigned, but said it wasn't for the reason she claimed.
According to a statement from the Miss Universe Organization, the contestant who Monnin claimed saw the sheet vehemently refuted Monnin's account.