Note to California Republicans: When your candidates start running for the lifeboats, maybe it’s time to reassess your strategy.

Nathan Fletcher, a GOP assemblyman who’s running for mayor of San Diego, jumped ship Wednesday, leaving the party and re-registering as a decline-to-state voter. It’s a decision, he said in a six-minute-long, YouTube video, that he’s been struggling with for some time.

“I believe it’s more important to solve a problem than to preserve that problem to use in a campaign,” Fletcher said in the video, which was “a plague on both your partisan houses” slam at both Republican and Democratic politicians. “I don’t believe we have to treat people we disagree with as an enemy.”

Sure, there’s a tinge of sour grapes in his decision, since he’s running a distant third in the race for mayor behind Republican City Councilman Carl DeMaio and Democratic Rep. Bob Filner. And he did lose the GOP endorsement to DeMaio earlier this month, which had to sting.

But think about this. Fletcher apparently decided that he’d have a better chance of getting elected mayor if he wasn’t a Republican. And that’s in San Diego, the most reliably Republican big city in California.

And Fletcher isn’t just any Republican. A 35-year-old former Marine, he was a decorated veteran of the Iraq war. He was elected to the Assembly in 2008 and is married to the former Mindy Tucker, a veteran GOP consultant who worked for both former President George W. Bush and ex-Gov. Arnold Schwarzenegger.

In a party with a noticeably short bench, Fletcher was seen as a rising star, someone who wasn’t too many years away from a run for statewide office.

But Fletcher ran into some uniquely Republican problems during his time in Sacramento. He supported gay rights measures, like Democratic state Sen. Mark Leno’s effort to require state textbooks to recognize the accomplishments of gays and lesbians. Fletcher voted for environmental legislation. He backed Gov. Jerry Brown’s jobs program and, horror of horrors, had the reputation of being willing to work with the Democratic leadership in the Assembly.

The party’s conservative base was quick to suggest that Fletcher was a RINO, or Republican in name only. Or even, they said with gasp, a moderate.

Tony Krvaric, the GOP chair in San Diego, called Fletcher’s choice a panicked effort to get back into the mayor’s race and suggested he was willing to do anything to get elected.

“It’s impossible to trust Nathan Fletcher,” he said in a release.

“Good riddance,” was the general GOP attitude.

Yet when your party registration in the state is at 30 percent and dropping, you don’t grow the membership by driving out young, photogenic war heroes for not being ideologically pure enough. You attract new supporters by convincing people like Fletcher to run for office as Republicans.

After all, it wasn’t that long ago that another relatively moderate former Marine named Pete Wilson could be elected assemblyman, San Diego mayor, U.S. senator and governor of California.

As Ronald Reagan once said, “My 80 percent friend is not my 20 percent enemy.”

Fletcher’s decision likely was his farewell to politics, since California isn’t a place that’s friendly to independent candidates. It’s a big, media-driven state where it takes serious bucks to run even a local campaign and that money isn’t easy to come by without the backing of a party and its allies.

Still, with the Legislature strangled by partisan gridlock courtesy of Democrats and Republicans more interested in scoring political points than dealing realistically with California’s problems, it’s hard not to feel sympathy with a relative newcomer like Fletcher, who was not happy with what he saw in Sacramento.

I’m leaving partisan politics, he said, “because I could care less about playing games.”

John Wildermuth is a longtime writer on California politics.