Endorsements and coattails never have meant much in California politics. From Ronald Reagan, whose strong efforts could not keep major state offices in Republican hands after his first term as governor, to Jerry Brown, who usually endorses only after fellow Democrats have already been assured their party’s backing, big names have not had much influence over voters.

The most classic example of lagging coattails came in 1980, when Mr. Reagan carried California in the presidential election by a record margin, but Democratic U.S. Sen. Alan Cranston won reelection with a larger edge. Even Arnold Schwarzenegger, who easily won election twice, pushed through fewer than half the ballot propositions he endorsed and never ushered a single fellow Republican into statewide office.

That’s why it may be premature for Democrats to celebrate, as they quietly have, the negative feelings most California voters have about Republican presidential nominee Donald Trump.

Democrats hope Mr. Trump will be a gift that gives them plenty this fall, wishing he will depress GOP turnout even though more Republicans than ever voted in the June primary election – 2.1 million in all, 1.55 million for Trump. Of course, Democrats more than doubled the springtime Republican vote, drawing some 4.5 million ballots into the contest between party nominee Hillary Clinton and Vermont Sen. Bernard Sanders.

All this matters because Democrats fervently want to hang onto their current 39-14 margin in California’s delegation to the House of Representatives and would also love to regain the brief two-thirds majority they held two years ago in the Legislature, which gave them virtually complete control of Sacramento.

Possibly the biggest beneficiary of a small Republican turnout might be Sacramento County’s two-term Democratic Rep. Ami Bera, in the midst of a fund-raising scandal where his father will do jail time after fraudulently raising larger-than-legal campaign donations for him.

What Scandal?

This story broke in media around Mr. Bera’s district just before the primary, but he still got 53.2 percent of the June vote, compared with 46.8 percent for incumbent Republican county Sheriff Scott Jones. Under the state’s Top Two system, even though Mr. Bera got a clear majority of the primary vote – he and Mr. Jones were alone on the ballot – the pair must face off again in November.

Mr. Bera’s fund-raising problems won’t go away before the election, and some voters who cast early ballots for him in the primary might not have known about the issue before they voted. So Mr. Jones has hope, but probably needs a strong GOP vote to oust Mr. Bera. That’s just one reason Democrats hope Mr. Trump depresses the Republican turnout.

With voters also due to decide hot-button issues from the death penalty to continued tax surcharges on the wealthy, from legalized recreational marijuana to requiring condoms in pornographic films, there’s a good chance even Republicans who detest Mr. Trump will vote.

So Democrats and supposedly independent political action committees backing them have begun sending out campaign mailers associating Mr. Trump with every Republican they can think of.

That happened this spring in the sprawling Los Angeles County supervisorial district held for more than 25 years by the termed-out Republican Michael Antonovich. He now seeks a state Senate seat. One mailer carried photos of five Republicans seeking the powerful county job, calling them “part of Donald Trump’s Republican Party.”

The mailer, sent for Democrat Darrell Park, helped him into the November runoff against Mr. Antonvich’s former chief of staff, Republican Kathryn Barger, in an area that has often elected GOPers to Congress and the Legislature. The Democratic hope, plainly, is that antipathy for Mr. Trump will drive some Republicans away from the polls.

California’s history indicates this won’t work. For one thing, it’s impossible here to pull a single lever and cast a vote for any party’s full slate of candidates. Because each office requires a separate vote, chances are most Republicans won’t think about Mr. Trump when they reach the congressional and legislative parts of their ballots.

This means Democrats should be concentrating on turning out their own voters this fall, not worrying about depressing the GOP vote. If they do that well, the Republican turnout won’t matter much, except in a few places, because there are so many more registered Democrats here than Republicans.

Mr. Elias may be contacted at tdelias@aol.com. His book, “The Burzynski Breakthrough, The Most Promising Cancer Treatment and the Government’s Campaign to Squelch It,” is now available in a soft cover fourth edition. For more Elias columns, visit www.californiafocus.net