Sen. Bernie Sanders has opened a massive lead in Iowa, according to a new New York Times/Siena College poll.

The new numbers show 25 percent of Hawkeye State voters now say they support the Vermont socialist, with his nearest rival, former South Bend, Ind. mayor Pete Buttigieg at 18 percent. Former Vice President Joe Biden and Sen. Elizabeth Warren — who have both at times led in Iowa polls — slipped to 17 and 15 percent, respectively.

The poll was taken between Jan. 20-23 and has a margin of error of 4.8 percent. The Iowa caucuses, the first test in the Democratic presidential race, are Feb. 3.

The Sanders surge comes even as the senator himself remains bottled up in the US capitol serving as a juror in President Trump’s impeachment trial. He is expected to fly back to Iowa (on a private jet) Saturday evening for a rally in Ames with New York Rep. Alexandria Ocasio-Cortez.

The poll suggests the 78-year-old lawmaker has escaped days of negative headlines stemming from a dispute with Warren over whether he once told her that a woman could not be elected president. Warren insists he did, while Sanders has strenuously denied it. Sanders has also had to contend with the wrath of his old 2016 rival Hillary Clinton, who blasted him in a new Hulu documentary.

“Nobody likes him, nobody wants to work with him, he got nothing done. He was a career politician. It’s all just baloney and I feel so bad that people got sucked into it,” she said.

“It truly looks like the attacks on Sanders backfired,” Jordan Uhl, a liberal activist and Sanders supporter, told The Post. “Corporate-backed Dem party loyalists attacking Sanders, to some extent, plays into his hand because it reinforces, to voters, what they already suspected: that the Democratic Party does not care about them.”