SAN JOSE, Calif. — When Rep. Kevin McCarthy was elected to Congress just eight years ago, he became part of a trio soon known as the “Young Guns,” the faces of a younger generation that would map the GOP’s future.

Now two of those guns have misfired — Paul Ryan wounded in his unsuccessful 2012 bid to be vice president, Eric Cantor felled in last week’s primary upset in Virginia. But McCarthy, R-Calif., is about to complete his transition from young gun to old hand, all but a shoo-in to succeed Cantor as majority leader when the GOP caucus votes today.

He’ll be a GOP leader from one of the nation’s most solidly Democratic states — in fact, the most powerful House Republican California has ever produced. This might contribute to conservatives’ distrust, but might benefit the Golden State’s Republican House candidates if he uses his new clout to help them stump and raise money.

“Part of Kevin’s Achilles’ heel is that he comes from a blue state, and traditionally those who rise to leadership tend to come from somewhere their party has been in control,” said Jon Fleischman, a former state GOP vice chairman who runs the FlashReport.org conservative news site and is politics editor of Breitbart California.

Rep. Raul Labrador, R-Idaho, is McCarthy’s only challenger for the House’s No. 2 leadership post, arguing McCarthy isn’t conservative enough and is too closely aligned with Cantor and Speaker John Boehner, R-Ohio.

“To do the same thing again after the message that grass roots sent in the Cantor race seems crazy to me,” said Matt Kibbe, president and CEO of FreedomWorks, a Washington-based conservative grass-roots group backing Labrador. McCarthy’s ascent “doesn’t bridge the divide between the younger reform-minded members and the GOP establishment,” Kibbe said.

McCarthy remains the odds-on favorite, and he’s unopposed for re-election to a fifth term this year. But his rise and his changing district mean he’ll have to walk a fine line, and Kibbe notes the House GOP will take new leadership votes after November’s election.

Some tea partyers distrust McCarthy for favoring a path to legal status, though not full citizenship, for some immigrants in the country illegally. But back home, his largely rural district — including most of Kern and Tulare counties, with a bit of northeastern Los Angeles County as well — is 35 percent Latino, the agriculture-heavy business community supports immigration reform, and activists picket his office regularly.

The district’s Latino population will keep growing and national pressure will keep building, United Farm Workers President Arturo Rodriguez said Tuesday.

“McCarthy could find himself majority leader for a very short period of time and have no chance at the speakership,” Rodriguez said. “If he’s thinking long term and thinking, ‘I want to be the speaker at some point,’ he’d better focus on representing his constituency.”

While helping GOP House candidates raise money and attention in San Francisco in 2012, McCarthy said “you’re either a thermometer or a thermostat” — a thermostat being someone who not only can take a room’s temperature but also knows how to change it.

He sees himself as a thermostat. He’s an outspoken critic of California’s high-speed rail project, battles Democrats on the state’s water policy, and arguably is the GOP’s point man on wooing Silicon Valley.