With Israeli Prime Minister Benjamin Netanyahu set to address the Center for American Progress (CAP) Tuesday afternoon, progressive groups and figures—as well as its own staff—are expressing outrage that the influential, Clinton-tied think tank would provide a platform to a proven enemy of human rights and peace.

Organizations including the U.S. Campaign to End the Israeli Occupation picketed the institution on Tuesday morning and plan to return just before Netanyahu’s afternoon speaking engagement.

“We believe very strongly that a policy institute that calls itself progressive should not be providing space for the Israeli prime minister to spread his message of hatred, racism, and apartheid towards the Palestinian people,” Josh Ruebner, policy director for the U.S. Campaign, told Common Dreams.

In the context of national politics, CAP’s invitation to Netanyahu is no small matter.

CAP is already playing a powerful role in the 2016 presidential race, due to the close ties of its top leadership to former Secretary of State Hillary Clinton. In fact, CAP founder John Podesta—a longtime powerful operative in Washington—is heading Clinton’s presidential campaign. Tanden also has a close relationship with Clinton, as the policy director for her former presidential campaign.

Clinton, meanwhile, has been broadly criticized for her hawkish agenda, from Syria to Iraq to Israel. Last week, Clinton released a policy statement entitled “How I Would Reaffirm Unbreakable Bond With Israel—and Benjamin Netanyahu.”

After Netanyahu’s invite, many are sounding the alarm.

In an open letter to CAP published on Sunday, over 100 “progressive leaders and organizations”—including activist and writer Naomi Klein, playwright and activist Eve Ensler, MoveOn.org co-founder Noah T. Winer, Jewish Voice for Peace, and the Arab American Institute—declared that CAP has “made a mistake” in inviting the prime minister.

The letter cites Netanyahu’s call in 1996 for an end to the Oslo accords; opposition to President Barack Obama’s push in 2011 for a peace process based on the 1967 border; and vigorous lobbying against the nuclear deal between world powers and Iran.

“Netanyahu knows that he has created a deep partisan divide in the U.S. over Israeli policies and is attempting to repackage his increasingly far-right agenda as bi-partisan consensus,” the letter states. “CAP should not be providing him with this opportunity.”

What’s more, CAP’s invitation put the institution to the right of many in the Democratic Party, including the nearly 60 Democratic lawmakers who boycotted Netanyahu’s speech to Congress in March over the prime minister’s attempts to undermine the Iran nuclear accord.

But perhaps most stunning is the large number of current and former CAP staff members who have come forward to oppose Netanyahu’s address.

At a staff meeting on Friday, roughly a dozen CAP employees “stood up and delivered an impassioned joint statement criticizing CAP’s decision to hold the event, read aloud by a designated speaker,” Foreign Policy reported on Monday, citing unnamed sources who were in the room. The staffers, in particular, highlighted Netanyahu’s role in the recent Gaza war, which killed an estimated 2,134 Palestinians, approximately 70 percent of whom were civilians. According to the article, those staffers received an “enthusiastic round of applause” in the presence of CAP leadership.

And among the signatories to Sunday’s letter was Zaid Jilani, a former blogger forThinkProgress—the publication affiliated with CAP. Jilani told Common Dreams he signed on because CAP “is a political institution and it chooses who to invite based on politics. It is legitimizing Benjamin Netanyahu despite his abhorrent treatment of Palestinians and attacks on diplomacy with Iran. It is telling that it has invited no Palestinians to offer an actual debate with Netanyahu.”

Numerous other former staffers have come forward, including Ali Gharib, who worked at CAP in 2011 and 2012, wrote in The Nation last month that Netanyahu’s invitation was “jarring, but ultimately not surprising.”

“My stint there was defined by an attack on my and my colleagues’ work by pro-Israel groups; our taking a progressive stance on the Israeli-Palestinian conflict and pointing at pro-Israel figures as leading the charge for a war with Iran in Washington had attracted the attention of some of the Israel lobby’s nastiest apparatchiks,” he wrote.

Naomi Dann of Jewish Voice for Peace told Common Dreams: “Netanyhau has proven time and time again that he has no interest in peace, whatever platitudes he has said. We see that through his continued expansion of settlements, with 2,200 new homes announced yesterday. We see that through his escalation of violence against Palestinians, particularly over the last month, but it’s been happening for the last 50 years.”

CAP has long faced criticism for being beholden to corporate donors, falsely representing itself as progressive, and caving to the lobbying muscle of AIPAC and other pro-Israel advocates.

In an article published last week, Intercept journalist Glenn Greenwald reported on leaked emails which show that Neera Tanden, president of CAP, and key aides have engaged in “extensive efforts of accommodation in response to AIPAC’s and [Israel activist Ann Lewis’] vehement complaints that CAP is allowing its writers to be ‘anti-Israel.'” The emails confirm the accounts of Gharib and other former staffers who faced severe censorship.