UC Berkeley law Professor John Yoo is a hero in conservative circles for writing the Bush administration’s legal opinion that OKd waterboarding as an interrogation technique.

Republican front-runner Donald Trump is sympathetic to that view in that he favors “a lot more than waterboarding.”

But it doesn’t go both ways: Yoo would never vote for Trump. In fact, Yoo said that if Trump becomes the GOP nominee, the legal scholar would consider — consider — voting for a Democrat.

“I have never in my life voted for a Democrat for president,” Yoo said. “This would be the first time I’d think about it.”

That’s a snapshot of how concerned some prominent Northern California conservatives are about the 2016 Republican presidential candidates. Their opinions are influential as the state heads to its June 7 primary, which, with 172 delegates up for grabs, will be pivotal in determining the party’s nominee.

For while the Bay Area is the nation’s progressive soul, it is also home to some of the country’s most prominent establishment conservatives, including former Secretaries of State George Shultz and Condoleezza Rice (who declined to comment), as well as deep-pocketed donors Silicon Valley entrepreneur Floyd Kvamme, who, along with wife Jean, has contributed $200,00 to a pro-John Kasich super PAC, and venture capitalist Jillian Manus.

Many of them are nauseated by Trump’s divisive comments on immigrants, Muslims and women, and regret the establishment-splintering chaos the Republican primary has produced as the original field of 17 candidates has dwindled to three.

They use such words as “miserable,” “sickened,” “ashamed.” And most alarming for Republicans candidates everywhere, they’re not opening their checkbooks.

By this point in the election season, “I would have been knee deep in one of the campaigns,” said Manus, who campaigned for GOP gubernatorial candidates Meg Whitman and Arnold Schwarzenegger. But “I haven’t given one cent to a candidate. Actually that’s not true. I gave to Kamala Harris,” a Democrat running for U.S. Senate.

Cathie Bennett Warner, who worked on campaigns for President Ronald Reagan and former Gov. Pete Wilson, has been “just horrified by it. I’m horrified by the whole process. I was a delegate to four conventions, but not this year. I didn’t get involved with any campaign, not involved in any way, shape or form.”

Those closed checkbooks are particularly painful as the liberal Bay Area is also one of the nation’s top fundraising locations for conservatives. Bay Area Republicans may be a bit more moderate, but they’re generous. Collectively the region gave $33 million to Republican federal candidates and conservative causes in the 2012 presidential election cycle, according to the Center for Responsive Politics.

But this year, many conservatives are frozen by Republican mayhem and only a hardy few remain optimistic. Informally, they can be corralled into a few groups:

The never Trumpers: Representatives of this cohort, like longtime Republican political advertising executive Bob Gardner, aren’t shy about saying they are “very anti-Trump.”

“I’m old-fashioned in the sense that I do believe politics is a profession or a business,” said Gardner, who has worked on ad campaigns for Mitt Romney, George H.W. Bush, Gerald Ford and Dick Cheney. “And you don’t get to the CEO position without having been elected dog catcher.”

Constitutional scholar Yoo said: “By default, I can’t support Trump. He really is the kind of demagogue the framers (of the Constitution) were trying to stop: someone who was elected to office because he was popular and tried to play off the prejudices and biases of the moment. It was exactly Trump who they were afraid of.”

Some bad news for the never Trumpers: Trump is the GOP front-runner in the latest California Field Poll, with 39 percent support, compared with 32 percent for Sen. Ted Cruz of Texas. Ohio Gov. John Kasich trails with 18 percent among likely Republican voters. Trump holds the same lead over Cruz even among Bay Area Republicans, according to the poll.

Whither the GOPers: Several Bay Area conservatives say the chaos has them fretting about the future of the Republican Party.

“Ashamed. I think we all should be a bit ashamed,” Manus said. “I know that it doesn’t make complete sense, but I blame a lot of it on the Republican Party, because they wouldn’t move and listen to the moderate voice in the party and kept hanging onto these rigid conservative principles that are completely disengaged from the present, true needs of the Republicans.”

Peninsula real estate mogul Tad Taube, who has given millions to the conservative Hoover Institution think tank at Stanford University, worries that if no candidate has secured the 1,237 delegates needed to be nominated, then there could be some “disenfranchisement of our democracy” at the party’s national convention in July in Cleveland.

“I’m not crazy about either of them (Trump and Cruz), to tell you the truth,” he said. “But I’m frightened by the reaction we might get if we ignore those votes, then the establishment picks somebody.”

The silver lining option: Some GOP stalwarts are looking beyond the current chaos to the convention. Even Cleveland seems sunnier at this point.

“I’m an optimist,” Shultz said, “because I have seen many instances in our country where things were tough and we somehow pulled it out. ... But it takes leadership. And that’s what’s frustrating right now, and you don’t know who could do that. But conventions are fun.”

“An open convention is a good idea,” said Kvamme, who served as a science and tech adviser to President George W. Bush, “because it involves a large number of folks in the process.”

The Kasich maneuver: When these conservatives asked whom they were supporting, the name that popped up most was Kasich. Often by default.

Investor William Oberndorf, who supported former Florida Gov. Jeb Bush before he dropped out of the race, has since developed an appreciation for the practical joys of Kasich.

“As a lifelong Republican who is a conservative on fiscal issues and a liberal on social issues, I find Donald Trump and Ted Cruz so unacceptable that I will vote for Hillary Clinton if either of them become the nominee,” Oberndorf wrote in an email. “I believe the California primary will play a key role in determining whether there will be a nominee other than Trump or Cruz, which is why I am supporting John Kasich.”

With Trump not a possibility, Yoo said he’s deciding between “Kasich or Cruz. The deciding factor will be which one is best to defeat Hillary.”

“He’s sensible. He doesn’t go off on tangents,” said Kasich supporter Maurice Kanbar, founder of Skyy vodka and a Republican who has supported conservative Rep. Tom McClintock as well as Democratic Gov. Jerry Brown.

The nuclear option — Hillary Clinton: Any rock-ribbed conservative — even a Bay Area one — would have to be in a deep, dark place to cast a ballot for a member of the Clinton family, for decades the GOP’s nemesis. But the prospect of a President Trump has pushed some to the doorstep of darkness.

“To me, it’s anybody but Trump, but I have a really hard time with the other candidates,” said former Presidio Trust Chairwoman Nancy Bechtle, a registered Republican who has also supported Democrats including Sen. Dianne Feinstein.

Could she vote for a Democrat if Trump is on the top of the GOP ticket? “Oh, absolutely: Hillary,” Bechtle said. “This is America, you really want to have the best person be president.”

Never Clinton or Sanders: Rest assured that the vast majority of conservatives aren’t ready to tap the nuclear option if they don’t like the GOP nominee.

“I would not consider it, because no matter how bad the choices may be, the choices on the other side are ridiculous,” Taube said. “One (Clinton) is under danger of being indicted (in connection with controversy around her private email server). And the other (Sanders) is proud of the fact that he’s a socialist or a communist or whatever he says he is.”

Gap clothing co-founder Doris Fisher wouldn’t vote for a Democrat. “No. I may not even vote.”

Warner said she will consider voting for a Democrat if Trump is the GOP’s nominee, but “if it’s Bernie Sanders, I’ll probably leave the country.”

And Shultz, an eminence grise of the Republican Party, said “I don’t what I would do. I can always move to New Zealand. I understand it’s a nice country.”

Leah Garchik is a San Francisco Chronicle columnist, and Joe Garofoli is The Chronicle’s senior political writer. Email: lgarchik@sfchronicle.com, jgarofoli@sfchronicle.com Twitter: @leahgarchik, @joegarofoli