California Gov. Gavin Newsom said he will not run for president in 2028 if former Vice President Kamala Harris enters the race, saying a contest between the longtime California political allies would be a “waste of everyone’s time.”

Newsom made the declaration Monday to CNN’s Jake Tapper while the two were fly fishing in Montana’s Bitterroot River as part of a wide-ranging interview about the governor’s life, political career, and possible presidential ambitions.

“I don’t know if she runs, but we’ll see,” Newsom said. “I wouldn’t run if she ran.”

Asked why, Newsom replied, “Of course not. Why would I? I wouldn’t do that to her. I wouldn’t do it to me.”

He added that he would not “waste everyone’s time” by fighting Harris for the nomination.

“Who needs that?” he told Tapper.

Neither Newsom nor Harris has announced a 2028 campaign, though both have indicated they are considering a run, reports The Washington Post.

Newsom, who is barred by term limits from seeking another term as governor, has increasingly raised his national profile and traveled outside California ahead of the midterm elections.

Newsom said competing against Harris would amount to “mutual assured destruction” because the two Democrats share many of the same political supporters and connections.

“First of all, electorally it’s a gift from God for everybody else,” Newsom said. “They’d enjoy the hell out of it. Mutual assured destruction. It serves no greater good.”

Newsom said the overlap between their political networks would make a head-to-head campaign particularly difficult.

“I know her base of supporters, I know her friends, the [Venn] diagram on that is just pure crossover,” he said. “I wouldn’t do that to people. I wouldn’t put them in that position.”

Newsom and Harris have moved through California politics alongside one another for more than two decades.

Newsom served as mayor of San Francisco before becoming lieutenant governor and then governor, while Harris served as San Francisco district attorney and California attorney general before being elected to the U.S. Senate and later becoming vice president.

Harris unsuccessfully sought the Democrat presidential nomination in 2020 and became the party’s nominee in 2024 after then-President Joe Biden ended his reelection campaign. She lost the general election to President Donald Trump.

Newsom faced speculation during the 2024 campaign that he could emerge as an alternative to Biden, but he backed Harris after Biden withdrew.

In the CNN interview, Newsom said he had not been prepared to seek the presidency at the time.

“I would have gotten crushed because I didn’t have a why,” he told Tapper. “You don’t have a big enough why, then you don’t belong there.”

Newsom said any future presidential decision would require him to determine whether he has a reason compelling enough to enter what could be a crowded Democrat field.

“You gotta be honest with yourself,” Newsom told Tapper. “Do you represent the zeitgeist of the moment?”