Gavin Newsom has paid for billboard banners in Mississippi, Texas and several other Republican-run states in the lead up to the November midterms. The California governor’s campaign has aired TV advertisements in Florida, and he’s challenged the state’s governor, Ron DeSantis, to a nationally televised debate.

No, he’s not running for president. At least, not officially.

Newsom easily trounced a recall effort last year and is expected to coast into re-election in November. With a healthy lead in statewide polls and a hefty $24m in his campaign fund, Newsom is using the opportunity to raise his national profile – and maybe bask a bit in the presidential buzz surrounding him.

He has insisted that he has “subzero interest” in being president, and he reiterated the point during a talk last week in Austin, where he was billed to speak “on what the nation’s most populous state” could teach the other 49.

“I cannot say it enough,” Newsom said. “I never trust politicians, so I get why you keep asking.”

But denial is the tradition of pretty much every politician who has flirted with chief executive ambitions. Why else is he touting his visits to the White House (to “meet with national leaders” and pick up an education award) and speaking engagements in New York (to amplify his climate policies)?

“Yeah, he’s definitely running for president,” said Dan Schnur, a politics professor at the University of California, Berkeley, who has advised Republican candidates. “The only question is whether he’s running in 2024 or 2028.”

With Joe Biden suggesting that he will probably run for re-election, Newsom might have to wait his turn. In any case, “Newsom is setting a course for higher office, after his tenure as governor,” said Sonja Diaz, director of UCLA’s Latino Policy and Politics Institute. Nearly every California governor since the second world war has harbored presidential hopes, but Newsom could just as well be auditioning for the Senate seat that the 89-year-old Dianne Feinstein might retire from soon, or perhaps some other national position in Washington DC.

It’s not just Newsom’s campaign that has raised chatter about his national aspirations. Opinion columnists, political consultants and activists have also closely watched his gubernatorial priorities and vetoes – and wondered about his motivations.

Diverging at times from his own professed policy ideals, Newsom has attempted to walk the line between California progressivism and nationally appealing moderation. He pushed to keep open the state’s last nuclear plant, going against an agreement devised with environmental groups years ago. He successfully championed a controversial program to force unhoused people into mental health and substance abuse treatment, over the objections of civil rights leaders, disability activists and healthcare professionals. And last month, he vetoed a bill that would have allowed for supervised injection site pilot programs in Los Angeles, San Francisco and Oakland – backtracking on his own support for such measures to prevent overdose deaths. “I have long supported the cutting edge of harm reduction strategies,” he said in a veto message, but he said the bill “could induce a world of unintended consequences”. Ultimately, he kicked the can down the road, directing the health department to research “best practices” for such programs.

“A centrist Democrat who needs to win swing voters in the general election can’t sign legislation creating government-run drug sites,” Schnur said. Based on his personality, his business-minded background and his policy track record, Newsom isn’t likely to inspire the party base the way progressives like Bernie Sanders could. “So his opportunity lies in really presenting himself as a center-left alternative,” Schnur said.

Newsom’s office declined to comment on this story but directed the Guardian to news releases and public comments explaining his reasoning for vetoing legislation. His re-election campaign also did not respond to the Guardian’s queries.

Having risen to political prominence from the Bay Area, backed by some of San Francisco’s wealthiest families, Newsom will have to expand his circle of advisers, consultants and surrogates – to better understand and reach across the state and country, Diaz said.

As a career politician who rose from San Francisco parking and traffic commissioner to mayor to lieutenant governor to governor, and as a multimillionaire businessman, with a chain of wineries, restaurants, nightclubs, hotels and shops stretching across northern California, Newsom has benefitted throughout his career from his close ties with the Gettys, politically well-connected heirs to an oil fortune.

And so far, Newsom has had to face few – if any – truly competitive political challenges. Currently, he has the backing of 52% of registered voters, compared with 25% who favor his challenger, Brian Dahle, a conservative state senator. Even during his recall election last year, when California voters showed signs of losing faith in Newsom amid a devastating surge in the Covid-19 pandemic and escalating economic woes, the governor was able to easily retain his seat – and defeat conservative and rightwing challengers who inspired even less faith in voters.

In many ways, Newsom has made much more of an effort than many of his predecessors to elevate Latino, Black and Asian American leaders, and to engage with the state’s vast geography of cultures and experiences, Diaz noted. But in a national race, Newsom may have to do more to convince voters, especially voters of color and working-class voters, that he really sees and understands their challenges and the legacy of inequality that they have to contend with, she said. So far, even the governor’s well-intentioned policies amid the pandemic exacerbated racial and economic disparities.

Although Newsom ultimately signed a farmworker labor bill to ease union voting, his initial hesitancy threatened to alienate California’s large unions, agricultural workers and their families, and other essential workers. In a rare moment of intervention, Biden has urged Newsom to sign the measure, which would ease farmworker union voting, as did the House speaker, Nancy Pelosi, Newsom’s longtime Bay Area ally.

The pressure came after Newsom’s office issued a statement last month suggesting that he would veto the measure, and the governor declined to personally meet with United Farm Workers representatives who organized a march from the San Joaquin Valley all the way to the capitol.

“In the state with the largest population of farmworkers, the least we owe them is an easier path to make a free and fair choice to organize a union,” Biden said, just before Labor Day.

The statement is in line with Biden’s broader support for unions. “But it’s not hard to imagine that the president wanted to remind the governor to wait his turn,” Shnur said.