Nassau County Executive Bruce Blakeman formally announced his New York gubernatorial bid Tuesday, setting up what could be a costly and contentious Republican primary against Rep. Elise Stefanik.

“Our state is struggling under policies that have driven up taxes, utility bills, and crime. It’s time for a proven leader who will Put New York First,” Blakeman said in a Facebook post announcing his candidacy.

“New Yorkers deserve leadership that works — not more empty promises,” he added. “I’m ready to take on Kathy Hochul and get results for our families.”

The Long Island politician said he’d be Republicans’ best bet to win the general election in November 2026 to unseat Hochul in the deeply blue Empire State.

“I’ll say to Democrats and independents, what have you got to lose?” he told The Post Tuesday.

Blakeman said he’d campaign by talking to New Yorkers about how he could make their lives better as governor.

“I’m going to talk about public safety, economic development, lowering taxes, making New York more affordable and putting New York first,” he said.

In a brief interview with The Post after his announcement, he didn’t mention Stefanik by name when asked about her attacks.

“I’m going to run against Kathy Hochul, and I’m going to run on my record,” He said.

Blakeman, 70, also released a campaign video to accompany his announcement, touting Nassau County as the “safest in America” — in part due to cooperation with the Trump administration’s crackdown on illegal immigration.

He bragged that Republicans fared well on Long Island in the November elections, bucking a trend of Democratic victories across the country.

President Trump has not said whether he will make an endorsement in the primary. He nominated Stefanik to be ambassador to the United Nations last year before withdrawing her name to help secure the slim Republican House majority.

“She’s great. He’s also great,” the president said Monday of the two contenders, adding that “I’ll think about” whether to make an endorsement.

Locally, Nassau County GOP Chair Joe Cairo was quick to get behind Blakeman.

“Bruce won re-election overwhelmingly in a county with more than 110,000 more registered Democrats than Republicans – proof that voters trust his leadership,” Cairo said in a statement. “Bruce Blakeman will beat Kathy Hochul. And Bruce Blakeman will save New York State.”

Stefanik’s campaign went on the attack, releasing a statement shortly after his pending entry to the race was revealed Monday, saying he’s “putting his raging ego first and New Yorkers last.”

The North Country pol already has a significant backing amongst party big-wigs, including 58 of the 62 county committee chairs and state party Chairman Ed Cox.

She spent the evening posting quotes on X from GOP County committee chairs and state lawmakers who have already endorsed her.

Hochul welcomed the developing Republican clash.

“If there’s a Republican primary, it makes it much more entertaining for me,” she told reporters at an unrelated event Monday.

“It doesn’t matter which Trump cheerleader decides to run against me. The narrative is the same,” she added.