Outrage is mounting on Capitol Hill over efforts by an anonymous member of Congress to organize an anti-Israel forum with a number of advocacy organizations that support boycotts of the Jewish state, according to multiple conversations with sources who are attempting to identify the member of Congress behind the event.

The Washington Free Beacon first disclosed on Tuesday that a delegation of anti-Israel advocacy groups had been circulating an invitation to a June 8 event on Capitol Hill that is meant to build congressional support for efforts targeting the Israeli military for alleged human rights abuses.

The event, which is sponsored by a member of Congress who has chosen to remain anonymous despite calls for the individual to step forward, is being organized by a who’s who of anti-Israel advocacy groups that have supported Israel boycotts and been cited for distributing propaganda slandering the Jewish state.

Pro-Israel officials on Capitol Hill have begun a search to out the member behind the forum following the Free Beacon’s initial report, according to sources familiar with the situation.

Rep. Peter Roskam (R., Ill.), co-chair of the House Republican Israel Caucus, told the Free Beacon on Wednesday that taxpayer resources should not be used to fund an event backed by those advocating boycotts of Israel.

"It's completely unacceptable to use the resources of the House of Representatives to help promote the hateful, malevolent BDS [Boycott, Divestment, and Sanctions] campaign," Roskam said. "If a Member of Congress wishes to sponsor an event like this, he or she should step forward and tell us why."

The event, "50 Years of Israeli Military Occupation & Life for Palestinian Children," is scheduled to be held June 8 in room 122 of Capitol Hill's Cannon House Office Building, according to an invitation viewed by the Free Beacon.

Space for events of this nature must be reserved by a member of Congress, who typically shows up in person for the event. However, lawmakers can reserve a room and choose not to step forward publicly.

This was the case last year when Rep. Sheila Jackson Lee (D., Texas) anonymously reserved space for an advocacy group that aimed to hold the first-ever congressional forum in favor of boycotting Israel. News of the event sparked outrage and eventually forced Jackson Lee to admit to backing the event, which was later cancelled and moved to a space off of Capitol Hill.

One senior congressional official engaged in efforts to name the lawmaker sponsoring next month’s event told the Free Beacon that there is no appetite in Congress for events of this nature.

"It's telling that a member brazen enough to sponsor radically anti-Israel events like this one is simultaneously unwilling to do so publicly," the source said. "Hiding behind a cloak of anonymity while facilitating this propaganda is cowardice in its most basic form. The vast, overwhelming majority of members who recognize that Israel is our strongest ally deserve to know which of their colleagues is behind this."

Democratic leadership additionally told the Free Beacon that they do not know which member is sponsoring the event, another sign that the person behind the event is attempting to keep their name a secret.

An aide for Rep. Steny Hoyer (D., Md.), the House Minority Whip and staunch pro-Israel voice, further told the Free Beacon that the lawmaker’s office was not aware of who is backing the event.

Groups involved in organizing the event include several advocacy organizations known for their criticism of the Israel Defense Forces, or IDF. They include the Defense for Children International-Palestine and American Friends Service Committee, which operate an affiliated advocacy group dedicated to accusing the IDF of various crimes against humanity.

These organizations have been cited by pro-Israel organizations and watchdog groups for their promotion of anti-Israel propaganda and false information about the IDF.

Speakers scheduled to attend the event include: Omar Shakir, the Israel and Palestinian director for Human Rights Watch, which routinely criticizes Israel; Brad Parker, the staff attorney and international advocacy officer for Defense for Children International-Palestine, a group that backs Israel boycotts; Nadia Ben-Youssef, director of the Adalah Justice Project, which has accused Israel of "genocide"; and Yazan Meqbil, a Leonard Education Scholar and student at Goshen College.

Israeli Lt. Col. (Res.) Maurice Hirsch, who until recently served as the Head of the Israeli Defense Force's Military Prosecution for Judea and Samaria told the Free Beacon that the organizations behind the Hill event routinely disseminate propaganda to undermine Israel's defense operations.

"The Palestinian Authority and its agents —such as DCI-Palestine—and other anti Israel groups constantly attack Israel using distorted ‘facts' and invented fallacies regarding Israel's treatment of Palestinian minors," Hirsch said. "They use inflated, irrelevant statistics and promote a blind narrative that all Palestinian minors are subject to ill treatment by Israeli Authorities."

However, these organizations ignore the Palestinian Authority's efforts to indoctrinate children to hate Israel and pursue terrorism.

"They ignore the clear ‘child abuse' suffered by the minors at the hands of the Palestinian Authority that indoctrinates them to hate Jews, glorifies terrorists and terrorism and sanctifies martyrdom," Hirsch explained. "Were the incitement and the terrorism to end, and were the Palestinian Authority to abandon these innocuous practices, the lot of the Palestinian minors would improve immensely. The upcoming ‘Peace not Walls' conference is not likely to be any different."

Update 3:58 p.m.: This post has been updated to reflect comment from Maurice Hirsch.