Gov. Gavin Newsom has revealed one factor that could tank his expected presidential bid: fellow Democrat Kamala Harris.

Newsom was asked in an interview with CNN’s Jake Tapper about his expected White House run, and he didn’t hold back on how the former vice president, his former colleague and rumored frenemy, could change his decision.

“I wouldn’t run if she ran,” Newsom said while fly-fishing with Tapper in Montana.

“I wouldn’t do that to her … I wouldn’t waste anyone’s time,” Newsom explained, calling it “mutually assured destruction.”

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The governor, who recently returned from a much-publicized trip to South Carolina — recently named as Democrats’ first presidential primary state — said he wasn’t sure if his fellow California Dem will actually launch a bid.

However, he suggested that the two have extensive “crossover” in their friends and supporters, claiming to Tapper: “I wouldn’t do that to people.”

It would be a “gift from God for everybody else,” if the two California Dems both ran, he said.

Harris, who has unsuccessfully run for president twice already, is leading many early polls of potential Democratic contenders. Newsom’s odds on the prediction market Polymarket fell to 7% last week as possible rivals including Bronx Rep. Alexandria Ocasio-Cortez and Georgia Sen. Jon Ossoff appear to gain traction.The former veep has been busy this year visiting key states for the 2026 midterms and the 2028 presidential primary, including stops this spring in South Carolina and Nevada. A source with knowledge of Harris’ operations told The Post that a Democratic National Committee staffer left the party to go work for her this year.

“Staff is being deployed to key states. Political circles are talking about how the presidential primary calendar is in her favor,” the source said, referencing South Carolina and Nevada as the first two states to vote.

“Whether or not donors would support her running again, though? Those are all factors to consider.”

Newsom and Harris’s history dates back decades, when they were respectively mayor and district attorney of San Francisco.

The governor has said previously that he would only run for president if all of his four children, who are between the ages of 10 and 17, agree to it.

The governor recently told PBS that two of his children are for it, while two are currently against the idea.

Newsom and wife Jennifer Siebel Newsom are facing legal pressures as federal investigators probe their finances.

Siebel Newsom’s taxes are one target of multiple investigations touching on Newsom’s orbit.

The San Francisco Standard reported last week that investigators have also subpoenaed records related to the governor’s travel, much of which is funded by the nonprofit California Protocol Foundation.

Newsom has dismissed the investigations as a political hit job.