GOP front-runner Donald Trump charged that Democrat Hillary Clinton lacks the “stamina,” “energy” and “strength” to be president — and he griped that the Republican Party’s requirement to win at least 1,237 delegates is “very unfair” — during a CNN presidential forum last night.

“She’s always got problems, whether it’s Whitewater or whether it’s emails,” Trump said about Clinton. “It’s always drama. … Honestly, she should not be allowed to run based on the emails. … She’s being protected. Hillary Clinton does not have the stamina, doesn’t have the energy, doesn’t have it, doesn’t have the strength to be president in my opinion.”

Trump lamented the GOP rules requiring the nominee win 1,237 delegates as “very unfair,” because the race has had up to 17 candidates, dividing the electorate.

“I have had many, many people running against me,” Trump said. “Mathematically, it’s unfair. It’s almost impossible to believe I should do that, that I would be able to do that.”

Trump denounced violence at his rallies and said he has no idea why white supremacist groups have publicly endorsed his campaign.

“I don’t know,” said Trump, “because I’m the least racist person that you’ll ever meet.”

Trump indicated he’s open to the possibility of a Trump hotel in Havana, Cuba. He said he believed it was a “slight” that Raul Castro did not meet President Obama at the airport when he arrived in Cuba.

Trump also once again insulted Fox News Channel host Megyn Kelly, calling her a “third-grade talent” who “does negative hits on me … every night on her show.”

“If she didn’t talk about me, her ratings would go down like a rock,” Trump said . “She’s hotter now than ever before because of me. She should give me at least half her salary.”

Both U.S. Sen. Ted Cruz and Ohio Gov. John Kasich in their interviews ruled out the idea that they’d be Trump’s running mate in a general election.

“There is zero chance I’d be vice president for either of them,” Kasich said of serving under either Cruz and Trump. “Zero. Below zero, actually.”

Cruz said, “If Donald Trump is the nominee, it’s a disaster. Hillary wins. Donald may be the only candidate on the face of the planet that Hillary Clinton can beat in a general election and the stakes are too high.”

The CNN forum, called “Final Five,” was a series of separate one-on-one interviews, moderated by Anderson Cooper and Wolf Blitzer.

In her interview, Clinton reacted to criticism that she yells in campaign speeches.

“I don’t hear anybody say that about men,” said Clinton. “And I’ve seen a lot of male candidates who don’t smile very much and who talk very loud.”

Sanders denied he’s hurting Clinton’s general election chances by staying in the race, saying he expects his campaign will do well in Utah, Idaho, Washington, Alaska, Hawaii, Oregon and California.

“I think we have a road — a narrow road — but a road to victory,” Sanders said.