One of Florida’s biggest conservative Republican moneymen — and a billionaire backer of Jeb Bush — is so disgusted by Donald Trump’s candidacy that if he has to, he’ll do the unthinkable:

“If I have a choice — and you can put it in bold — if I have a choice between Trump and Hillary Clinton, I’m choosing Hillary,” Miami healthcare magnate Mike Fernandez told the Miami Herald on Friday. “She’s the lesser of two evils.”

Outraged by Trump’s unimpeded ascent, Fernandez is taking on the GOP frontrunner himself. He purchased a full-page ad in the upcoming Sunday edition of the Herald calling Trump a “narcissistic BULLYionaire with a hunger to be adored.” He also likened him to some of history’s bloodiest demagogues.

“You have no idea how furious I am with my friends in the Republican Party who have embraced this guy,” Fernandez said.

Fernandez, who also plans to run the ads in Des Moines and Las Vegas newspapers on Dec. 14, said he didn’t notify the Bush campaign of his plans. Fernandez was the single highest donor to the political committee backing Bush, Right to Rise USA, as of the last financial disclosure report at the end of June. His contribution: more than $3 million.

“My frustration is really with that sector of Republican voters that are so blinded by the demagoguery” of Trump, Fernandez said. “I know the campaign — or any other campaign — is not going to say it.... This is not about Jeb. This is about us. This is about the voter.”

By saying he’d pick Clinton over Trump, Fernandez took a bolder stance than Bush himself, who said on CBS News’ Face the Nation last Sunday: “Anybody is better than Hillary Clinton,” though he added that he has “great doubts about Donald Trump’s ability to be commander in chief.”

Fernandez’s move comes as some Republican donors have started to organize against Trump, though their efforts so far have been scattered. Trump has flummoxed the party order, which assumed all along that the bombastic real-estate tycoon’s popularity would eventually fade. He has led polls nationally and in the early states of Iowa and New Hampshire for more than three months.

A CNN/ORC poll released Friday, 58 days from the Feb. 1 Iowa caucuses, showed Bush garnering only 3 percent support nationally. That’s 33 percentage points behind Trump, who at 36 percent polled 20 points ahead of his nearest competitor, Texas Sen. Ted Cruz. Bush and his allies have spent more than any other contender on TV ads: nearly $30 million.

Dario Moreno, a Florida International University pollster backing Florida Sen. Marco Rubio for president, said confronting Trump will take a lot more than a few ads in local newspapers.

“To make an impact on a national race in states, you have to buy TV or direct mail,” he said. “This is an indication of how unsettled some of the Bush backers are. Fernandez is trying to be helpful, but I don’t think it’s going to be effective.”

Fernandez sent the ad, which was first reported by Politico, to various news outlets — and, he said, to “103 friends who are equally frustrated.” Upon learning about his plans, the Bush campaign “chewed me out,” he said, though Fernandez still plans to attend a Saturday gathering of Bush donors and campaign staff. A Bush spokesman declined to comment.

Perhaps most striking in the ad is its comparison of Trump and several dead dictators.

“Look at Hitler in Germany, Mussolini in Italy and Peron in Argentina,” it says. “When people lose hope, they are susceptible to those who offer to think for them.” (“I’m not comparing him to Mother Teresa and a guardian angel,” Fernandez quipped.)

Notably absent from the list: Cuba’s Fidel Castro.

“He’s too old, and he’s useless,” said Fernandez, one of the most prominent Cuban-American Republicans to favor President Barack Obama’s renewed diplomatic ties with the island. “If I put Fidel, it becomes a Cuba thing.”

The Trump campaign did not respond to an emailed request for comment.

Fernandez, who chairs MBF Healthcare Partners, left Cuba for the U.S. at age 12 in 1964. He said Trump’s rhetoric about illegal immigration pains him. Last year, Fernandez published an autobiography, Humbled by the Journey, about growing up in exile. He has also tried to build a 425-foot-high “Flag of Gratitude” in the city of Miami.

In 2014, he parted ways with Republican Gov. Rick Scott’s reelection campaign — Fernandez had been its finance co-chairman — a few weeks after calling out Scott staffers when a Hispanic business partner of Fernandez’s overheard them crudely mimicking a Mexican accent on their way to a Coral Gables Chipotle restaurant.

“I’m just a freaking immigrant, so no one is going to listen to me. But this is like a kick in the teeth,” Fernandez said of Trump’s candidacy. “It just bothers me that Americans could be fooled this way.”

Trump and his supporters, Fernandez predicted, are “laughing behind our backs.”

“America should stop being played like a patsy,” he said. “Once you start down this path, it is very dangerous.”

Asked if Trump could win the general election, Fernandez was adamant.

“Hell, no,” he said. “He will not win, because he’s unelectable.

“But he will cause some good people to lose.”