WASHINGTON—  Sen. Bernie Sanders, I-Vt., called out top leaders in both parties on Tuesday for welcoming Netanyahu to Congress, excoriating the Israeli prime minister as a “war criminal” amid the ongoing war with Gaza. 

In an interview with NBC News Tuesday, Sanders lashed out at House Speaker Mike Johnson, R-La., for inviting Netanyahu to address a joint session of Congress in the coming weeks.

“What Mr. Johnson is going to have to explain to the American people is why he thinks it’s okay to invite somebody to a joint session who is responsible for the deaths of some 38,000 Palestinians at this point, 60% of whom are women and children, elderly people,” Sanders said. (The U.N. cited a death toll of more than 36,000 Palestinians as of May 31.)

Reminded that Senate Majority Leader Chuck Schumer, D-N.Y., as well as the minority leaders of both chambers, joined Johnson’s invite to Netanyahu, Sanders said he “strongly” disagreed with the decision.

Asked if he voiced that disagreement to Schumer, Sanders dryly laughed. “I have made it very clear to anybody who would listen,” he said.

His comments come as a growing group of Senate Democrats are expressing concern that Netanyahu’s address could be politically divisive, further exacerbating tensions in Congress and frustration with the Israeli military campaign. A date for the speech has not yet been set.

Senate Majority Whip Dick Durbin, of Illinois, the number two Senate Democrat, said Tuesday that he would not have invited Netanyahu to speak before Congress until the Israeli prime minister commits to a two-state solution. Durbin said he is concerned the address could be a reprise of Netanyahu’s controversial speech to a joint session in 2015 when he criticized the Obama administration’s policy towards Iran.

“That’s exactly the fear I have is that it would be politically divisive, it would not help Israel,” Durbin told NBC News, “I’m waiting for clarity on the two-state solution, I think that is a central part of our strategy and I’m waiting for him to commit to it.”

Both Sens. Peter Welch, D-Vt., and Jeff Merkley, D-Ore., also said they disagreed with extending an invitation to Netanyahu to address Congress, with Welch saying he’s “undecided” on whether he would attend the speech. Both Welch and Merkley voted against the aid bill for Israel and Ukraine in April, citing their opposition to the Israeli military operation as the reason for not supporting the package.

Sen. Brian Schatz, D-Hawaii, said he believes Netanyahu “has been bad for Israel,” saying: “If he’s gonna come here and make a political speech then I think he should stay home and try to negotiate a peace agreement.”

But Sen. Chris Murphy, D-Conn., says he plans to attend the speech, saying, “I’m always willing to listen to foreign leaders, even those that I disagree with.”

“I reserve the right to be surprised,” Murphy said, “But my sense is that his appearance here may be more about trying to buoy his political standing back home than actually trying to effectuate peace or improve the relationship between the United States and Israel.”

Sanders made clear he will not attend the speech, though he noted that his office does have televisions. He will “probably listen,” he said.

But, Sanders said, boycotting the speech by refusing to attend in person “is a statement of whether or not you think somebody who has acted in such a horrific way deserves the honor of speaking to a joint session. That is an honor.”