There are now four major Democrats and three Republicans running for governor. In California, that means there are too many Republicans in the race.

Hey, that’s not just my opinion. Ask Jim Brulte, chairman of the California Republican Party.

“We have three excellent candidates running for governor,” Brulte said the other day after Republican and former Sacramento congressman Doug Ose jumped in the race. “And if all three stay in, we run the risk of having an all-Democrat runoff.”

So at least one of the GOP candidates has to go, for the sake of voters who want the chance to choose a Republican for governor in November. And for the sake of every other California Republican running for office this year.

Brulte’s evaluation is based in the raw math of California’s top-two primary system and the dwindling appeal of Republicans west of the Sierra.

Roughly 39 to 41 percent of the votes in the June 5 primary are expected to be cast for Republicans, according to Paul Mitchell, vice president of Political Data, which provides voter information to campaigns and pollsters in both parties. About 59 to 61 percent is expected to be cast on the Democratic side of the ticket.

The two other Republican candidates — businessman John Cox of Rancho Santa Fe (San Diego County) and Assemblyman Travis Allen of Huntington Beach (Orange County) — are pulling about 9 percent each, according to the December Berkeley IGS Poll. That leaves 23 percent available to Ose and the dozens of unknowns who typically clamber onto the ballot. (Two Democrats, Lt. Gov. Gavin Newsom and former Los Angeles Mayor Antonio Villaraigosa, top the Berkeley IGS Poll.)

Ose, whose name recognition doesn’t extend far beyond the Sacramento area, would have to attract virtually all of that remaining Republican support to be one of the top two finishers who advance to the general election in November.

That’s unlikely at this point.

With three candidates in the race, “It gets very hard to do the math to find some scenario where a Republican gets enough votes to slip into the runoff,” Mitchell said. “It’s a math problem. It makes a Dem-on-Dem race more likely if you continue to split the Republican vote. Especially if one of those Republicans doesn’t catch fire (with voters).

“One (GOP candidate) has to break 20 percent, and they will make it into a spot in the runoff,” Mitchell said.

And if one Republican doesn’t make the runoff, then it’s bad news for every down-ballot Republican. Analysts say if voters aren’t excited about the race at the top of the ticket — governor or U.S. Senate — or a provocative ballot measure, they may not vote.

That leads to another problem. Republicans really need a GOP gubernatorial candidate on the November ballot because they’re unlikely to have anybody running for Senate. With no major GOP candidate in the race, the Senate campaign is shaping up to be a Democrat-versus-Democrat battle between incumbent Sen. Dianne Feinstein and state Senate President Pro Tem. Kevin de León, D-Los Angeles.

Hey, that’s not just my opinion. Ask Shawn Steel, the Republican national committeeman who has been a top party official for decades.

“Numberswise it doesn’t look good,” Steel said this week.

So maybe it is time for a party elder — like, say, Shawn Steel — to pull one of the gubernatorial candidates aside and say something like, “You really don’t want to be governor, do you? It’s really a terrible job. Why not take the summer off?’

“They never appreciate that advice,” Steel said.

No, they don’t. In fact, the three Republicans are doubling down on staying in the race.

Cox, who is largely funding his campaign with his own money, pulled another $1 million out of his wallet last week after Ose jumped in. He’s already put $3 million of his own cash into his campaign.

On Thursday Allen, the only candidate on the GOP side without deep pockets, was on Twitter breathlessly touting the results of a rather suspect new survey that showed, in his capitalized letters: “TRAVIS ALLEN NOW TOP REPUBLICAN FOR GOVERNOR.”

Unmentioned in Allen’s tweet is that the survey also included dozens of candidates, real and imagined, like Democrat Steve Westly and Republican Ashley Swearengin, the former mayor of Fresno. Both said months ago that they’re not running.

As for Ose, he said nobody told him not to run. Just the opposite.

“In fact,” Ose told me this week, “most of the people inside the (GOP) institutional interests have told me quietly and privately, ‘Hallelujah.’”

One can see how mainstream Republicans would welcome Ose. Cox has never held elective office, and Allen is a three-term Assemblyman who doesn’t have much statewide name recognition and hasn’t been a fundraising machine. Ose was a three-term congressman who left office because he promised voters he’d serve only three terms in Washington. However, in 2014 he ran for Congress again, and lost to Rep. Ami Bera, D-Elk Grove (Sacramento County), by only 1,455 votes.

Perhaps equally alluring to Republican Party officials is the prospect that Ose, a wealthy real estate developer, would self-fund his campaign. That means the party wouldn’t have to help him raise money.

That, however, is not going to happen.

“Self-funding is a mistake,” Ose said. “It’s been proven to be a cul-de-sac for most campaigns. If you do that, you get branded as a wealthy white person who is trying to buy the race. If you can or can’t raise money, that’s a testament to what you’re offering people. I will go raise the money to fund my campaign.”

So there you have it. The California Republican Party is stuck with three candidates for governor. Three guys who have no intention of leaving the race.

“You got to wonder,” Steel told me. “Is someone going to blink?”

Not unless someone makes them.

Joe Garofoli is The San Francisco Chronicle’s senior political writer. Email: jgarofoli@sfchronicle.com Twitter: @joegarofoli