A progressive candidate for governor of Illinois was deserted by endorsers and supporters last night, after he bowed to pressure and ditched a running mate who had been critical of Israel.

State Sen. Daniel Biss, a Democrat who had entered the crowded gubernatorial primary as a “progressive champion,” had aggressively sought the support of left-wing groups like Reclaim Chicago and Our Revolution. They were thrilled last week when he announced Chicago alderman Carlos Ramirez-Rosa, a member of Democratic Socialists for America, as his candidate for lieutenant governor.

“We need someone who is a progressive in their core, who is unafraid to take on entrenched power, and unashamed to always stand with the working families of Illinois,” Biss said.

The bold pick got Biss some national attention; Ramirez-Rosa, 28, is perhaps the biggest political star in the resurgent democratic socialist movement and had been a 2016 DNC delegate for Sen. Bernie Sanders (I-Vt.). But within days, Biss was taking friendly fire over DSA’s endorsement of the Boycott, Divestment, and Sanctions (BDS) Movement, which was approved by members at the group’s summer convention, and of his running mate’s own stated position on Israel.

“You know, for too long the U.S. government has subsidized the oppression of the Palestinian people, and it’s time that that’s stopped,” Ramirez-Rosa told the Real News Network, a progressive website, last year. “And we have seen a shift internationally in favor of justice for the Palestinian people. You know, people stand with Israel, but they also want to make sure the Palestinian people have [justice].”

On Sunday, one of Biss’s highest profile supporters, Rep. Brad Schneider (D-Ill.), wrote on Facebook that he had been shocked to learn of the Ramirez-Rosa pick, and would be withdrawing his endorsement.

“I remain hopeful that, as Alderman Ramirez-Rosa learns more about the importance of the US-Israel partnership to both our nations, the unique challenges Israel faces as the only democracy in a very dangerous neighborhood, and the commitment of the vast majority of the Israeli people to peace and a two state solution, he will reconsider his positions,” Schneider wrote.

Within 72 hours, Ramirez-Rosa was out, and in embarrassing fashion. Biss announced on social media that Ramirez-Rosa had previously told him that he opposed BDS, and had apparently changed his mind — a characterization the alderman disputed.

“Growing up with an Israeli mother, grandparents who survived the Holocaust, and great-grandparents who did not survive, issues related to the safety and security of the Jewish people are deeply personal to me,” Biss said.

In short order, endorsers began criticizing or dumping Biss, and volunteers in some parts of Illinois bolted his campaign. (“Worse than Palin IMO. At least McCain stuck with her,” said one Illinois Democratic source.) The Chicago branch of Our Revolution, Sanders’s political network, issued a statement of “disappointment and shock” with Biss’s move.

“With Carlos on the ticket, many were encouraged that important issues like Medicare for all, the fight for a $15 minimum wage, affordable child care and free college tuition would be part of the agenda for Illinois,” Our Revolution wrote.

Ramirez-Rosa quickly moved on, pointedly telling Politico that he might end up supporting another candidate for governor, and meeting up with supporters in Chicago for an impromptu party.

Biss had previously been seen as a long-shot contender in the crowded Democratic primary, just six months away. Chris Kennedy, a philanthropist and son of the late Robert F. Kennedy, was seen as an early front-runner; J.B. Pritzker, a billionaire investor, had jumped in later and scooped up most key labor endorsements. In the short run, Biss’s lack of a running mate limits his ability to circulate petitions for a place on the ballot. (Kennedy has yet to choose a running mate.)

Gov. Bruce Rauner (R-Ill.), a billionaire elected in the 2014 Republican wave, is seen as one of the most vulnerable incumbents in next year’s elections.