A top surrogate for Donald Trump said he is convinced the GOP establishment is behind the leaked the lewd audio and video recordings that have shaken up the presidential race.

Jerry Falwell Jr., president of Liberty University, which bills itself as the largest Christian University in the world, told WABC radio host Rita Cosby that Mr. Trump’s caught-on-tape comments are indefensible, but said that he thinks the release of the tape was planned to give Republicans an excuse to “slither out” of supporting the GOP presidential nominee.

“I think it was timed,” Mr. Falwell said. “I think it might have even been a conspiracy among establishment Republicans who have known about it for weeks and who tried to time it to do the maximum damage to Donald Trump, and I just … I just think it just backfired on them.”

Mr. Falwell said his charge is based on “some independent information” he has received, but he refused to name names.

“But I think some of the establishment folks who reluctantly endorsed him had this planned all along as a way to slither out of the endorsement, and I think it backfired on them, and I’m glad to see that,” Mr. Falwell said.

He also said that he is not surprised that the recordings were leaked ahead of Mr. Trump’s scheduled appearance with House Speaker Paul Ryan, who has tepidly embraced the brash businessman.

“It wasn’t a coincidence that it came out right before Trump was supposed to appear with Paul Ryan at a rally, and it conveniently gave Paul Ryan a way to disinvite Trump,” Mr. Falwell said.