Gavin Newsom and John Cox are preparing for a general election battle to decide who will be California’s next governor, but much of what they plan to focus on has little to do with how either candidate would lead the state.

Instead, both men are engaged in proxy campaigns for other candidates and causes.

Front-runner Newsom will spend significant time trying to help Democrats flip seven California congressional seats that are crucial to the party’s efforts to retake the House, a win that would provide a counterweight to President Trump and his policies. Republican Cox will campaign for a ballot measure to repeal an increase in the state’s gas tax, hoping the effort lights a populist fire among California voters that draws in Democrats and independents.

In an environment in which voters are not particularly tuned in to the governor’s race, working on behalf of other campaigns is a smart move, some political strategists said.

“Neither one of them is in a position to motivate their party’s base, so they both turned to something else to do it for them,” said Dan Schnur, a veteran political analyst who teaches at USC. “There is nothing for California Democrats as motivating as Donald Trump, and there’s nothing as motivating for California Republicans as the repeal of the gas tax. Both candidates have figured out it’s a lot easier to surf a wave than it is to create a new one.”

Newsom said he will launch a fall bus tour of the seven congressional districts that voted for Hillary Clinton in the 2016 presidential election and are represented by Republicans in Congress. His campaign plans to rally supporters in those districts to volunteer for Democratic hopefuls, as well as legislative candidates who can help the party reclaim a two-thirds majority in the state Senate.

Newsom, the state’s lieutenant governor and a former mayor of San Francisco, is tapping an email list of several hundreds of thousands of supporters to help his preferred candidates.

He sent fundraising appeals for Democrats Katie Hill, who is running in the 25th Congressional District against Rep. Steve Knight (R-Palmdale), and Josh Harder, who is running in the 10th District against Rep. Jeff Denham (R-Turlock). Last week, Newsom challenged his supporters to donate $25,000 in less than seven hours to support the seven congressional candidates and his campaign.

“Switching things up … because 2018 is about so much more than just our race. We have to take back the House in November, and the road to the House goes through California,” Newsom wrote in an email. “This is how we take control of our future and stop Trump’s bigoted agenda: We elect strong progressives up and down the CA ballot.”

Because he is not facing another Democrat in a costly general election fight, Newsom said, he’s able to help other candidates.

“We have the opportunity to unify our party, and unification is not just organization, it’s not just human resources. It’s also capital … making sure we are fundraising aggressively,” he said at a recent news conference in Los Angeles. “And that’s one specific, tangible way that I can be helpful.”

Cox has been a major booster of Proposition 6 on the November ballot, which would repeal a $52-billion transportation law enacted last year that increased taxes on gas and diesel sales and created a new annual vehicle registration fee to finance road and highway repairs.

As chairman of the repeal effort, Cox has spent $250,000 of his own money to back the campaign — and might contribute more. He frequently discusses the tax on the campaign trail, arguing that Sacramento Democrats are out of touch, fail to live within their means and harm hardworking Californians with their policies.

Californians have “had enough,” he said in a June interview, noting that he heard a Democrat call a radio program earlier in the day to voice frustration over paying $4.10 a gallon for gas, a price he blamed on the new tax. “The affordability, which includes the gas tax, is going to be a major issue.”

The candidates’ strategies have ancillary benefits.

Republicans believe the gas tax has the potential to incite voter outrage among Californians of all political stripes, as the tripling of the state vehicle license fee did in 2003. The move paved the way for the recall of Democratic Gov. Gray Davis and the election of Gov. Arnold Schwarzenegger. At one point on the campaign trail, the Republican dropped a wrecking ball on a car symbolizing the fee.

In 1978, rising property taxes led voters to approve Proposition 13, the property-tax limiting measure that is a third rail in California politics.

“I really think that Proposition 6 could be the Proposition 13 of this decade,” said former state GOP Chairman Ron Nehring, pointing to the recall of state Sen. Josh Newman (D-Fullerton) this year over his vote for the gas tax increase. “Democrats have overreached, they can’t dial it back, and now you’re seeing a real tangible result of that. It’s a perfect crossover issue [and] it’s a winning issue for us.”

Nehring said Cox’s decision to focus on repeal of the gas tax increase was smart because of its potential to attract Democratic and independent voters, but he acknowledged that Cox faces a tough battle running for statewide office in California as a Republican.

There is more support for repeal than for Cox, according to USC Dornsife/Los Angeles Times polling this year. The repeal was supported by 51% of registered voters in a May poll, while Cox was backed by 28% in a June survey.

Bob Shrum, a former Democratic political operative who is the director of the Jesse M. Unruh Institute of Politics at USC, said the numbers show the difficulty for any Republican to get elected statewide in California, particularly one with Cox’s views on abortion and other issues that are not shared by many of the state’s voters.

“After 2016, I won’t say anybody is unelectable, but the fact of the matter is it is very hard to come up with a plausible case that Cox can win this election,” Shrum said. “He is so out of step with Californians on social issues, on immigration. And he’d like to run on the gas tax, but the problem with that is voters can repeal the gas tax on its own, they don’t have to vote for him to do it.”

For Newsom, his focus on congressional races allows him to avoid unforced errors in the governor’s race, in which he has overwhelming leads in the polls, and to build chits for a potential future run for higher office, said Darry Sragow, a veteran Democratic consultant.

“He can earn a lot of credits and put them in the bank for later,” Sragow said. “He can foster a national presence without looking overly ambitious. It’s all upside, a lot of opportunity to do good deeds, win friends, influence people and stay out of trouble.”

seema.mehta@latimes.com

Twitter: @LATSeema