Donald Trump slammed Ted Cruz's father Rafael Cruz for his attempts to court the evangelical vote in Indiana, which hold its primary today, and even brought up a tabloid report that links the elder Cruz to the Kennedy assassination.

'I think it's a disgrace that he's allowed to do it,' Trump said of Rafael Cruz's vocal attempts to recruit Body of Christ evangelicals in the Hoosier State.

But then the billionaire went a step further.

'You know his father was with Lee Harvey Oswald prior to Oswald being shot,' Trump mentioned. 'The whole thing is ridiculous ... and nobody even brings it up. They don't even talk about that. That was reported and nobody talks about it.'

Trump was repeating tabloid claims made in this week's National Enquirer cover story, which links the elder Cruz to Oswald, who would go on to assassinate President John F. Kennedy.

At a press conference several hours later, Ted Cruz lost it over this allegation.

' Donald Trump alleges that my dad was involved in assassinating JFK,' Cruz began.

'Now, let's be clear: this is nuts. This is not a reasonable position,' the candidate added.

'This is just kooky. And while I'm at it I should go ahead and admit yes, my dad killed JFK, he is secretly Elvis and Jimmy Hoffa is buried in his backyard,' Cruz said.

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Donald Trump (left) appeared on Fox & Friends this morning and blasted Ted Cruz's father Rafael Cruz (right) for his 'disgraceful' attempts to court the evangelical vote in Indiana. Trump also brought up a National Enquirer story that linked the elder Cruz to the Kennedy assassination

Sen. Ted Cruz spoke to reporters a few hours after Donald Trump made his comments about Rafael Cruz and said Trump's allegations were 'nuts' and 'just kooky'

A National Enquirer article claims this man (circled) is Rafael Cruz. The man on the far right is Lee Harvey Oswald, who is seen distributing propaganda about Fidel Castro's communist regime in New Orleans in 1963

The report uses a single photograph, from New Orleans in 1963, which depicts Oswald, alongside a man who was never identified by the Warren Commission.

The Enquirer pinpointed that individual as Cruz.

'There’s more similarity than dissimilarity... it looks to be the same person and I can say as much with a high degree of confidence,' Mitch Goldstone, president and CEO of ScanMyPhotos, told the Enquirer, comparing the young man to Cruz.

The man and Oswald, who was identified by the U.S. government in the photograph, were handing out pro-Fidel Castro literature to New Orleans residents on the streets.

The elder Cruz has been connected to the Cuban Communist leader before, with Ted Cruz publicly admitting that his father wanted to join astro's guerrilla army during the 1950s revolution which overthrew the Batista regime in 1959.

But prior to the National Enquirer there was no link between Cruz and Oswald, who was shot by Jack Ruby days after the Dallas killing of President Kennedy.

Once the report was out there, the Cruz campaign immediately pushed back.

'This is another garbage story in a tabloid full of garbage,' Ted Cruz's communications director Alice Stewart told McClatchy. 'This story is false; that is not Rafael in the picture.'

But now Trump has peddled the report and made it part of the presidential race.

'What was he doing with Lee Harvey Oswald shortly before the death, before the shooting?' Trump said this morning on Fox & Friends, never once mentioning the late Democratic president's name. 'It's horrible.'

As for Rafael Cruz, he's become a vital campaign surrogate for his son, trying to cultivate support among Indiana's Body of Christ evangelicals.

The elder Cruz recently appeared on video making a pitch to that group.

'If the righteous are not running for office, if the righteous are not even voting. What is left? The wicked electing the wicked. And it becomes our fault,' Rafael Cruz said on camera.

'I implore, I exhort every member of the Body of Christ to vote according to the word of God. And vote for the candidate who stands on the word of God and the Constitution of the United States of America,' Cruz continued.

'And I am convinced it is my son Ted Cruz,' he added. 'The alternative could be the destruction of America.'

He asked evangelical voters in the state to look at the record instead of listening to the rhetoric and swiped at Trump, without saying the candidate's name, for the billionaire's abortion record.

Trump was previously pro-choice, though now says he's firmly pro-life.

This morning, Trump cut into the elder Cruz.

'And it's disgraceful that his father can go out and do that,' Trump said, pointing to the remarks Rafael Cruz made in the video. 'And so many people are angry about it.'