Donald TrumpDonald John TrumpSasse: Trump shouldn't dignify Putin with Helsinki summit Top LGBT group projects message onto Presidential Palace in Helsinki ahead of Trump-Putin summit Hillary Clinton to Trump ahead of Putin summit: 'Do you know which team you play for?' MORE on Tuesday slammed "disgraceful" comments from the father of his Republican presidential rival, Texas Sen. Ted CruzRafael (Ted) Edward CruzThe Memo: Trump leaves chaos in his wake in UK Beto O'Rourke is dominating Ted Cruz in enthusiasm and fundraising — but he's still headed for defeat GOP senators introduce resolution endorsing ICE MORE, who called on Christians to support his son in the Indiana primary.

“I think it’s a disgrace that he’s allowed to do it. I think it’s a disgrace that he’s allowed to say it,” Trump said during a telephone interview on "Fox and Friends."

Trump touted his support from Jerry Falwell Jr. and other evangelical supporters, saying, "It's disgraceful that his father can go out and do that and so many people are angry about it, and the evangelicals are angry about it, the way he does that."

Rafael Cruz, a minister, was speaking to a group of pastors in Indianapolis on April 25 when he made an appeal on behalf of his son, according to video posted on Facebook.

“I implore — I exhort every member of the body of Christ to vote according to the word of God and vote for the candidate that stands on the word of God and on the Constitution of the United States of America,” Rafael Cruz said in the video clip broadcast by Fox.

“And I am convinced that man is my son, Ted Cruz. The alternative could be the destruction of America," Rafael Cruz added.

Trump and Cruz are battling in Indiana on the day of the state's primary on Tuesday.

During his Fox interview, Trump invoked a tabloid story that claimed to link Rafael Cruz to John F. Kennedy's assassin, Lee Harvey Oswald, which Cruz's campaign last month dismissed as "garbage."

"His father was with Lee Harvey Oswald prior to Oswald being shot. I mean, the whole thing is ridiculous," Trump said. "Nobody even brings it up; they don't even talk about that."

"What was he doing with Lee Harvey Oswald shortly before the shooting?"