With a nuclear deal between Iran and other world powers “tantalizingly close,” civil society groups on Tuesday urged U.S. lawmakers to embrace the diplomatic process, back the agreement, and reject the “new push for war.”

In a letter released Tuesday, 40 U.S.-based organizations called on lawmakers to “vote in favor of an agreement when it comes before Congress and to commit to vote to uphold a Presidential veto should Congress vote against the agreement.”

Signed by numerous groups—including U.S. Labor Against the War, American Friends Service Committee, Jewish Voice for Peace, and National Iranian American Council—the letter continues: “The American public overwhelmingly supports a diplomatic resolution to the nuclear standoff with Iran and does not want another war.”

“We do not want to see the critical progress that American diplomacy has achieved over the past two years be derailed by some in Congress who prefer military adventurism over diplomatic solutions,” the letter states.