Sen. Bernie Sanders has urged Democratic leaders to ban super PAC spending in primaries, focusing on the efforts of pro-Israel lobbyists to influence a crucial Michigan Senate race.  

Sanders in an open letter on Sunday called on Senate Minority Leader Chuck Schumer, House Minority Leader Hakeem Jeffries and Democratic National Committee Chair Ken Martin to end a “corrupt system” of super PAC funding. 

His main target was the American Israel Public Affairs Committee, which spent $32 million in an unsuccessful bid to tank the Democratic primary campaign of Abdul El-Sayed, a critic of Israel, for a Michigan Senate seat. El-Sayed last week defeated Rep. Haley Stevens, a pro-Israel moderate.

Sanders cited reports that the pro-Israel lobby is now weighing another surge of funds to buoy Mike Rogers, the Republican nominee who will face El-Sayed in what is expected to be a tight general election in November.

“It is absurd that they spend tens of millions of dollars to try to determine who the Democratic nominee is and, if they fail, then proceed to support the Republican candidate in the general election,” said Sanders. He added that corporate PACs, including “crypto, AI and other online betting special interests,” have spent a record $517 million this election cycle. 

Sanders, an independent senator from Vermont who frequently caucuses with Democrats, has long pushed for a constitutional amendment to undo the Supreme Court’s 2010 decision in Citizens United v. Federal Election Commission, which allowed corporations to spend unlimited money on elections. He said in his letter that Democratic leaders did “not have to wait” for that, urging the party to immediately “prohibit super PACs from participating in its primaries.” 

“Millions of Democrats are AIPAC members who are proud to help elect principled Democrats,” AIPAC said Monday in its response to Sanders.

“This letter isn’t about democracy or campaign finance — that’s why he doesn’t name the billionaire super PACs that back him,” the group said on X. “Sanders just wants to blacklist Americans who disagree with him.”

Sanders acknowledged in an interview on CBS’s “Face the Nation” Sunday that Democrats would be severely disadvantaged if they forewent PAC spending in general elections, but said the party should “take charge of what takes place within their own primaries right now.” 

Sanders is the most prominent Jewish progressive in American politics. He has supported an insurgent wave of democratic socialists and Israel critics who won elections over the past year, including El-Sayed, Adam Hamawy, the victor of the Democratic primary in New Jersey’s 12th district, and New York City Mayor Zohran Mamdani. 

While Sanders built his movement on fighting economic inequality, he has increasingly condemned Israel’s attacks on Gaza and Iran, and last year became the first U.S. senator to say that Israel committed genocide in Gaza. In April, a record number of 40 senators voted for his “Block the Bombs” resolutions to ban certain weapons sales to Israel.