Sen. Bernie Sanders (I-VT) is set to join a rally in New York City next Thursday with Mayor Zohran Mamdani and a trio of candidates he is backing in closely watched House races, The New York Times reports.

The event, which will be held five days before the June 23 primary at the Kings Theatre in Brooklyn, will lend a jolt of momentum to Mamdani’s preferred slate of far-left congressional candidates — including democratic socialists Claire Valdez and Darializa Avila Chevalier, and Brad Lander, a former New York City comptroller who also ran for mayor last election cycle.

Sanders, who is seen as a godfather of the modern left, most recently appeared with Mamdani in April at a rally to mark the mayor’s first 100 days in office. The Vermont independent also swore Mamdani in at his inauguration in January.

The senator’s decision to appear at the rally next week, however, is notable in part because he will be aiding Mamdani in his efforts to unseat two Democratic incumbents, Reps. Dan Goldman (D-NY) and Ariano Espaillat (D-NY), who have drawn backlash from the left over their support for Israel and ties to the pro-Israel group AIPAC, a chief source of criticism in the races.

Several House progressive leaders, prominently including Rep. Alexandria Ocasio-Cortez (D-NY), have remained neutral in the primaries to unseat Goldman, who is defending his seat against Lander, and Espaillat, who is facing Avila Chevalier. Polling has indicated Goldman is in serious trouble, with Espaillat bracing for a closer race than he and his allies had expected. 

Sanders, one of the most vocal critics of Israel in the Senate, has not officially backed Chevalier, even though his appearance in his home borough of Brooklyn next week is all but tantamount to an endorsement. The anti-Israel activist, backed by the Democratic Socialists of America’s New York City chapter, has drawn scrutiny in recent days over past inflammatory online posts — including one accusing Sanders of promoting “liberal Zionism.”

Espaillat, a five-term congressman, has garnered support from some influential House progressives, including Reps. Greg Casar (D-TX), who chairs the Congressional Progressive Caucus, Pramila Jayapal (D-WA) and Maxwell Frost (D-FL).

Mamdani had reportedly promised to endorse Espaillat before he announced his support for Avila Chevalier late last month. He has continued to stand by her amid blowback over her old posts that are now featuring in attack ads.

Sanders has already endorsed Lander as well as Valdez, a DSA-backed state assemblymember now leaning into her opposition to Israel in campaign ads she has released during the closing stretch of her race against Antonio Reynoso, the Brooklyn borough president backed by retiring Rep. Nydia Velasquez (D-NY). Reynoso, a more traditional progressive, has described himself as an “underdog” in the primary, due to Mamdani’s high-profile support for Valdez.

Valdez shared a post on X Friday featuring a raised eyes emoji in response to news of the Sanders rally.

In a statement shared Friday with the Times, which cited sources familiar with the rally, Mamdani called the three primaries a “fight for the city we can afford” and “a Democratic Party driven by big ideas, not big money.”

Mamdani appeared alongside Chevalier, Lander and Valdez in a widely viewed TV ad that aired last week shortly after the Knicks had won the first game of the NBA finals.

Lander, who left the DSA over its promotion of an Oct. 8 Times Square rally celebrating Hamas’ terror attacks on Israel in 2023, insisted this week that his own appearance in the ad was not an endorsement of Avila Chevalier, who had joined that demonstration.

“I’m not supporting any other congressional candidates in New York City,” Lander told Jewish Insider, arguing that “different members of a team” he said was led by Mamdani “play different roles.”

His planned appearance with Avila Chevalier next week, however, is likely to draw further scrutiny to that explanation.

Lander did not respond to a request for comment about the rally.