California Gov. Gavin Newsom has tepid approval ratings in his home state as he prepares to leave office and launch a possible presidential bid — and a new poll could signal pitfalls ahead for the California Democrat’s national ambitions.

The Democratic governor netted 45% approval of his job performance and 46% disapproval from 625 registered California voters in a poll released by NBCUniversal Local and Telemundo Station Group.

The poll, conducted Sept. 21 to 24, shows a stark partisan split: About 93% of Republicans said he’s been doing a bad job, and a majority of Independents, at 56%, agreed Newsom is underperforming.

Political consultant Matt Rexroad told The Post that the biggest hurdle for Newsom may lie in the fact that voters outside of the state’s largest metro areas — the Los Angeles metro and the Bay Area — are particularly negative on the ex-San Francisco mayor.

In the largely rural Northern California region, which doesn’t include Sacramento or the Bay Area, only 28% of voters approved of Newsom’s performance in the poll, while 60% disapproved.

“This does not impact his Presidential campaign directly, but it does indicate that he does not know how to communicate with rural voters,” Rexroad said.

“The people of Iowa, New Hampshire, and South Carolina will not be impressed with a politician from California who wants to talk about being from 1) California 2) San Francisco and 3) now lives in Marin County,” he added.

Rexroad, as an example, flagged a new ad by the Republican Governors Association tying a Democratic gubernatorial candidate in Kansas to California as an example of the Golden State’s polarizing national rep. 

The poll also showed stark contrasts in gender, as the majority of men disapproved of Newsom’s job but the majority of women approved. Breaking it down by race, the majority of white Californians disapproved but the majority of Hispanics and Asians had a positive view.

About 74% of Democrats approved of Newsom’s job — but that may not be high enough when running a national campaign in a polarized political environment, added Morris Levy, an associate political science professor at the University of Southern California.

“In short, Democrats mostly support Newsom, and Republicans are overwhelmingly opposed,” Levy said.

“Some Democrats are also lukewarm on Newsom, or dissatisfied with his performance, and this could become an issue if he seeks the nomination.”

Much of that is due to partisanship, Levy said, where President Donald Trump’s approval ratings breakdown seem to be a “mirror image” of Newsom’s.

The poll did find that 66% of surveyed California Democrats said they would be inclined to vote for Newsom as the Democratic presidential nominee, compared to 15% who wouldn’t, but Levy noted that question doesn’t pit the governor against other options.

While his approval ratings among different age groups remained consistent, the poll may not tell the whole story should Newsom run for president, Levy said.

“Newsom has sought to position himself as a mainstream Democrat — tussling with Trump but also tacking toward the center on issues such as transgender athletes’ participation in female sports,” he said. “That probably masks the opposition Newsom or Harris would face from the surging younger portion of their base that has shifted far to the left on economic issues, Israel, and more.”

In recent months, the governor has made trips to early primary states like Michigan and South Carolina to test out his appeal.

He’s also made some policy announcements and stances that pundits have viewed as tacit shifts to appeal a left-leaning base of any potential presidential primary. For example, Newsom came out this year to support a national billionaire tax despite long opposing his state’s proposed billionaire tax measure.

The Post reached out to Newsom’s office for comment on the poll.