Donald Trump increasingly looks unbeatable in the Republican presidential nominating sweepstakes unless the GOP establishment can persuade a bunch of candidates to drop out early, conservative commentator Pat Buchanan said Friday.

Appearing on “The Laura Ingraham Show,” Buchanan said the dropouts likely will have to include Jeb Bush, the former Florida governor who previously looked invincible but whose fortunes have sagged under months of a withering onslaught by Trump.

“At some point, he does become an impediment to the establishment getting a comeback plan,” Buchanan said.

Trump, the billionaire real estate mogul and reality television star, continues to hold large leads in national polls and early state surveys. Buchanan said it is increasingly apparent that establishment forces cannot take Trump down with so many credible alternatives.

“It’s looking very, very difficult to see how they’re gonna take this nomination from The Donald,” he said.

“It’s looking very, very difficult to see how they’re gonna take this nomination from The Donald,” he said.

Buchanan suggested the establishment has a shot if it coalesces around a single candidate. And the best hope appears to be first-term Florida Sen. Marco Rubio, he said.

“He’s back in the pack, but he looks like the third horse coming around the far turn,” he said.

Trump terrifies the establishment, Buchanan said.

“He is not under any measure of control or discipline,” he said. “He’s a very entertaining candidate, and he’s full of verve and life. And I think he’s more disciplined than he was in July. And he’s putting on a great show.”

Buchanan compared Rubio to Rep. Paul Ryan, a Wisconsin Republican whom many are trying to entice to become speaker of the House of Representatives. He is “a likable guy,” as is Rubio, Buchanan said. But if Ryan becomes speaker, he almost certainly will pursue the same policies on trade and immigration that turned grass-roots conservatives against outgoing Speaker John Boehner, he said.

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And if Trump does take the nomination?

“All of a sudden, a lot of folks he was unaware they were supporting him are going to suddenly be around him. They’ll all be gravitating there. This city is full of people who want to work in the White House and in government and in the State Department and Defense and everything.

“And the closer Donald gets to that nomination, the more he’s going to hear from them.”