Lefty “Avengers” star Mark Ruffalo is wading into New York’s tight race for governor with a video telling Republican Lee Zeldin to “frack off.”

“Let’s keep our anti-fracking ally, Gov. Kathy Hochul, in office,” the “Hulk” actor urged his fans in a video he released on social media Friday — filling the message with questionable images purporting to show the dangers of fracking.

The clip included a two-second snippet from the 2010 anti-fracking documentary “Gasland” in which a man set his supposedly fracking-damaged kitchen tap on fire – a claim debunked by Duke University researchers in 2014.

“If you like clean water, if you like clean air, and not being poisoned, then let’s keep our Democratic governor in office,” Ruffalo, a long-time lefty activist, said, denouncing the Long Island congressman as “a far-right extremist wacko [who] wants to frack New York.”

“Gov. Hochul is doing a great job and she’s just getting started. Give her some time!” Ruffalo pleaded.

The spot, which earned about 201,000 views on Twitter by Saturday, ended with the Hochul campaign’s official logo.

Zeldin, who was polling 24 points behind Hochul as recently as August, has closed to within single digits of the incumbent in recent weeks — and supports plans to allow fracking in economically hard-hit regions of upstate New York.