Pennsylvania Sen. John Fetterman drew the line in the sand over his continued participation in the Democratic Party on Wednesday.

“If our party ever becomes — and just makes it official — the anti-Israel party, that’s when I would leave because that’s been a moral clarity for me,” he said during an interview at the Hill Nation Summit in Washington.

Fetterman, who has previously indicated that he had no plans to leave the Democratic Party, warned that if Democrats completely turn their backs on U.S. support for Israel, that would cross a red line that could push him out of the party.

The Pennsylvania Democrat says he has a major “concern” over the trajectory of many Democrats who have become increasingly critical of U.S. aid for Israel amid growing pressure from the party’s progressive base.

“My long-term concern has been with the Democratic Party, as I am a member of that, is that our party is going to back away and turn their back to Israel,” he said.

Fetterman cited Democratic support for an amendment sponsored by Rep. Thomas Massie (R-Ky.) to cut off $3.3 billion in annual security assistance to Israel and the success of progressive candidates who are harshly critical of Israel in Democratic primaries. The vote failed but had the support of 103 Democrats, including House Democratic Whip Katherine Clark (D-Mass.) and six of Pennsylvania’s seven “D” representatives.

Fetterman said Clark’s support for the amendment reflects a trend in the broader party.

“You look at the kinds of individuals that are winning our recent primaries,” he said. “It’s becoming more anti-, anti-Israel and hostile to people” who are pro-Israel.

He criticized fellow Democrats who “are trying to ingratiate ourselves with that segment of the base of our voters are intensely, intensely anti-Israel.”

And not mincing words, the former Pennsylvania lieutenant governor called progressives that have racked up recent elections wins the “dirtbag left.”

“Yeah, no, I mean, these — the kind of people they are trying to run out of office, they are just good, traditional kinds of Democrats you would expect in New York City now,” Fetterman told Fox News’s Sean Hannity.

“And now this has just become — really, it’s just been the dancing days of the dirtbag left. You know, some of these candidates are outrageous. You have candidates, they’re ‘abolish ICE,’ ‘abolish the police,’ ‘abolish the border.’”

The term “dirtbag left” refers to left-wing political critics who are generally supportive of progressive and democratic socialist causes and openly critical of mainstream Democrats. Writer Amber A’Lee Frost, one of the co-hosts of the “dirtbag left” podcast “Chapo Trap House,” is credited with coining the term.

Rep. Chris Rabb (D-Philadelphia), a Democratic Socialist and the recent winner of the Democratic primary in the 3rd Congressional District, criticized Fetterman, calling him a “sellout.”

“He has betrayed the people of Pennsylvania,” said Rabb. “He’s betrayed all of those people who thought he was different and better. The reality was he was only marginally different and far worse. Sadly, he was running as populist cosplay and he hurt a lot of people. It’s very easy to troll people who you find villainous. It’s much harder to actually govern and govern with integrity and from the moral center.”

Former New York City Comptroller Brad Lander, who defeated Rep. Dan Goldman in the Democratic primary for New York’s 10th Congressional District, told CNN’s Kaitlan Collins he was “not sure if Fetterman is in our party anymore, to be honest.”

“Democrats are having primaries to determine what kind of candidates we want to put on the field, and they‘ll be a diverse array of candidates because they reflect and represent a diverse array of districts,” Lander, another Mamdani-endorsed candidate, said. “Primaries are a time to have those fights out. And then, as we head toward the fall, it‘s a time of unity. I will try to be a force of unity.”