T. Boone Pickens, the oil tycoon who made and lost fortunes targeting some of the largest U.S. explorers over the past 40 years, said he supports Donald Trump for president and backed the presumptive Republican nominee’s call for a temporary immigration ban on Muslims.

Pickens, the chief executive officer of BP Capital, said at the SkyBridge Alternatives Conference in Las Vegas Wednesday that Muslims should be banned from entering the U.S. until they are properly vetted.

"Cut them off so we can figure out who they are coming in," Pickens told reporters at the conference. "We’ve got plenty of people here. We’ve got a good economy and Muslims coming into the U.S. I don’t see that impacting the economy at all."

Pickens, who earlier backed Jeb Bush, said Trump had seized on an opportunity because voters are “fed up” with politicians. Trump, a billionaire businessman and former reality-television star, had been largely self-funding his campaign. On Thursday, he named Steven Mnuchin, a hedge fund manager, to lead his national fundraising.

Pickens said he talked to Trump the day before yesterday and suggested he recharge the economy on the basis of cheap energy. When asked if he’s confident in Trump’s economic policy, Pickens said he’s been an economic success personally.

"So you judge a trapper by his pelt," Pickens said. "He’s done pretty well. Let’s see what he does. I haven’t seen his plan.”

He had harsh words for Hillary Clinton, Trump’s potential Democratic challenger, calling comments she made on energy policy “stupid.”

"If I don’t get Donald Trump, with change, I’m going to get Hillary Clinton," Pickens said in a Bloomberg Television interview with David Westin. "Now tell me, who are you going to vote for? There is no way you can vote for her."