Progressives are grappling with the killing of two people who worked at the Israeli embassy in Washington by a gunman who echoed a slogan that has become a rallying cry for many American liberals since the start of the war in Gaza.

After his arrest, the man suspected of killing the couple outside the Jewish Museum in Washington on Wednesday night exclaimed “free, free Palestine,” a phrase that has become ubiquitous at peaceful demonstrations and on social media over the past 18 months.

The attack brought renewed focus to a strain of violent radicalism on the left, even as progressives pointed out they share nothing with the gunman except his apparent support for Palestinian rights. What the attack did, they said, was hurt their cause.

“It betrays our values and hands more power to those already pushing authoritarian crackdowns,” said Layla Elabed, an organizer in Michigan and the leader of the Uncommitted National Movement, which arose in protest of U.S. support for Israel’s response to the Hamas attack launched on Oct. 7, 2023.

It’s also putting pressure on progressives to respond.

“Where’s our Martin Luther King today? I don’t know where that individual is. Who is that individual?” said a progressive strategist granted anonymity to speak freely. “We just don’t have big moral leaders in our society, period, let alone on the political front.”

A fringe, more radical wing of the pro-Palestinian movement has blinked in and out of national attention since the onset of the war in Gaza. Thousands of protesters have been arrested, including dozens who forcibly entered and occupied university buildings. And last year, POLITICO reported that an online network of pro-Palestinian activists in the U.S. included resources on how to “escalate” political actions beyond legal bounds, as well as pro-Hamas content.

Asked if members of the left are doing any soul searching, Kevin Rachlin — the Washington director of the Nexus Project, a left-leaning Jewish advocacy group — said, “I think they are.”

“This is more and more proof that we need to address antisemitism as a full society versus addressing [it] on the left or on the right,” Rachlin said.

Antisemitism historically and in recent years has more closely been associated with fringe groups on the alt-right, including most notably the 2017 “Unite the Right” neo-Nazi march in Charlottesville, Virginia. President Donald Trump himself dined with white nationalist and Holocaust denier Nick Fuentes at his Mar-a-Lago resort in 2022.

Supporters of the pro-Palestinian movement, including liberal lawmakers, found themselves on the defensive after the shooting outside the Capital Jewish Museum in a way that conservatives have had to respond to far-right violence in recent years.

Now, some pro-Palestinian activists worry the shooting, which federal authorities called a targeted act of antisemitism, could set back any progress they’ve made in their policy goals amid an increasingly dire humanitarian crisis in Gaza and an expansion of Israel’s military operation in the decimated territory.

“We hope and caution against this vigilante violence being used to undermine the movement to end the genocide, a movement of hundreds of thousands of Americans calling for ceasefire and arms embargo,” said Sandra Tamari, executive director of the pro-Palestinian Adalah Justice Project.

Alex Pascal, a former Biden administration official who helped craft its strategy to combat antisemitism, said, “We cannot allow this violence to be weaponized by those who might exploit it to further degrade our democratic rights and freedoms.”

Trump and Republicans for years have cast the pro-Palestinian movement as a group of radical terrorist sympathizers. As the Trump administration has taken increasingly severe steps to suppress the movement and punish its leaders, Democrats and advocates have pushed back on that characterization, framing Republicans’ actions as an attack on free speech.

Pro-Palestinian lawmakers rushed Thursday to condemn the murders and call them acts of antisemitism. Sen. Bernie Sanders (I-Vt.) said he was “appalled” by the “heinous act.” Rep. Alexandria Ocasio-Cortez (D-N.Y.) emphasized, “Absolutely nothing justifies the murder of innocents.”

Republicans were quick to paint the attacks as just part of broader extremism in the movement.

“The Palestinian cause is an evil one,” Rep. Randy Fine (R-Fla.) said Thursday on “Fox & Friends.” “The only end of the conflict is total surrender by those who support Muslim terror.”

As details about the attack emerged late Wednesday night, the Trump administration jumped into offense. Attorney General Pam Bondi and D.C.’s newly tapped interim U.S. attorney, Jeanine Pirro, visited the scene. And on Truth Social just after midnight, Trump wrote: “These horrible D.C. killings, based obviously on antisemitism, must end, NOW! Hatred and Radicalism have no place in the USA.!”

The left has had to walk this line before. Earlier this year, when federal immigration agents detained and moved to deport Mahmoud Khalil, a Palestinian green card holder and leader in last year’s pro-Palestinian protests at Columbia University, the Trump administration justified the arrest by claiming Khalil was a supporter of Hamas, a U.S.-designated terrorist organization.

Democrats have largely united around detained pro-Palestinian activists as victims of the Trump administration whose constitutionally protected political speech is under attack — but also hedged their statements by emphasizing they didn’t endorse Khalil’s opinions on the subject.

“I abhor many of the opinions and policies that Mahmoud Khalil holds and supports,” Senate Minority Leader Chuck Schumer said at the time on X. But, he added: “If the administration cannot prove he has violated any criminal law to justify taking this severe action and is doing it for the opinions he has expressed, then that is wrong.”

Holly Otterbein contributed to this report.