New York Democratic Sen. Kirsten Gillibrand (D-NY) is under fire from World Jewish Congress president Ron Lauder, who said he was “deeply disturbed” by her decision to withdraw her backing for anti-BDS legislation introduced by a fellow Democrat, citing the First Amendment as the basis for her choice.

On Monday, Gillibrand said she was withdrawing her name from the Israel Anti-Boycott Act, introduced by Sen. Ben Cardin (D-MD) in March and supported by 45 additional senators from the Republican and Democratic parties.

On Thursday, Lauder said he was “deeply disturbed” by Gillibrand’s announcement and noted that this bill was “aimed at combating the BDS movement which is spreading virulently in the United States and throughout the world.” According to the Algemeiner, he added, “I would urge Senator Gillibrand to instead add her name back as a co-sponsor for this legislation and reaffirm her commitment to opposing the international campaign to de-legitimize our democratic ally in the Middle East, Israel.”

The Israel Anti-Boycott Act “opposes the United Nations Human Rights Council resolution of March 24, 2016, which urges countries to pressure companies to divest from, or break contracts with, Israel” and “encourages full implementation of the United States-Israel Strategic Partnership Act of 2014 through enhanced, government-wide, coordinated U.S.-Israel scientific and technological cooperation in civilian areas.”

Gillibrand reportedly announced that she was withdrawing her support for the legislation at a town hall meeting in Queens where she cited the First Amendment — a position also held by progressive groups like the American Civil Liberties Union (ACLU).

In an op-ed last month, the ACLU wrote, “Last week, the ACLU came out against a bill that would criminalize constitutionally protected boycotts and certain speech targeting Israel. The Israel Anti-Boycott Act, which was introduced in both the House and Senate earlier this year, would expand a 1970s-era export law and expose a range of activity to sweeping penalties, including criminal prosecution.”

Cardin’s Israel Anti-Boycott Act seeks to amend the 1979 Export Administration Act “to include in the prohibitions on boycotts against allies of the United States boycotts fostered by international governmental organizations against Israel and to direct the Export-Import Bank of the United States to oppose boycotts against Israel, and for other purposes.”

This is not the first time the ACLU has targeted members of the Democratic Party over their support for Israel.

Last month, they went after Sen. Maggie Hassan (D-NH) for supporting the Israel Anti-Boycott Act, accusing her of stifling free speech.

“Senator Hassan strongly opposes the boycott, divestment and sanctions (BDS) campaign against Israel and believes that it harms efforts to secure enduring peace through bilateral negotiations toward a two-state solution,” Ricki Eshman, Hassan’s press secretary, said in a statement, according to the Algemeiner.

During Monday’s town hall, Gillibrand reportedly said, “I am against BDS, but I feel that anybody who’s in favor of it should feel very comfortable speaking on any stage, anywhere in America.” However, the Algemeiner notes that she specifically “avoided any mention of the link between the BDS movement and anti-Semitic statements and actions.”

In response to this, Lauder reportedly said, “Supporters of the BDS movement shield themselves by claiming that their movement is anti-Zionist, not anti-Semitic, but let me be crystal clear, anti-Zionism is no different than anti-Semitism. When you hold the only Jewish state to a different standard than every other nation, when you lie about its past and its present, that is old fashioned, unadulterated anti-Semitism.”

Adelle Nazarian is a politics and national security reporter for Breitbart News. Follow her on Facebook and Twitter.