WASHINGTON (JTA) — Hundreds of U.S. rabbis from the major streams of Judaism signed on to a petition urging Congress to oppose the Iran nuclear deal.

As of Tuesday morning, more than 840 rabbis had signed the online letter, which says that the hope for a good deal “is not yet realized.” The petition was posted on the Care2 website earlier this month and remains open until Sept. 7, with a goal of 1,000 signatures.

“Together, we are deeply troubled by the proposed deal, and believe this agreement will harm the short-term and long-term interests of both the United States and our allies, particularly Israel,” reads the letter, which was co-authored by Rabbis Kalman Topp of Beth Jacob Congregation in Southern California and Yonah Bookstein of Pico Shul in Los Angeles. “Collectively, we feel we must do better.”

The letter criticizes key aspects of the deal, including the lifting of the arms embargo on Iran and providing billions of dollars in sanctions relief without an “airtight, comprehensive inspections structure.”

In mid-August, a petition urging support for the nuclear deal with Iran signed by 340 U.S. rabbis from the major denominations of Judaism and sponsored by Ameinu, a liberal Zionist organization, was sent to Congress.

Congress will vote in September on whether to approve the deal reached between six world powers, including the United States, and Iran. The agreement offers Iran sanctions relief in exchange for scaling back its nuclear program. President Barack Obama has vowed to veto any legislation aimed at blocking the deal.