More than 300 liberal American rabbis wrote members of Congress Monday urging them to support the international nuclear deal with Iran, signaling the US Jewish community is split over the historic but controversial accord.

The religious leaders come from across the spectrum, but hail overwhelmingly from Judaism’s Conservative and Reform streams as well as other liberal, non-Orthodox Jewish movements, a spokesperson said.

“We encourage the members of the Senate and the House of Representatives to endorse this agreement,” the 340 rabbis wrote in a letter to Congress distributed by Ameinu, a liberal charitable Jewish organization.

“We are deeply concerned with the impression that the leadership of the American Jewish community is united in opposition to the agreement,” the rabbis added.

“We, along with many other Jewish leaders, fully support this historic nuclear accord.”  

The agreement, finalized last month after more than a year of intense negotiations, would roll back some aspects of Iran’s nuclear program in exchange for a lifting of economic sanctions.

Israeli Prime Minister Binyamin Netanyahu is strongly opposed to the deal. He argues it will fail to block Iran’s path to nuclear weapons that could be used to target the Jewish state.

Two weeks ago Netanyahu personally called on US Jewish groups to thwart the White House-backed deal. He made his appeal on a webcast hosted by Jewish American groups, which said it reached some 10,000 people.

He and other Middle Eastern leaders – as well as a growing number of critics – have warned that the deal only requires Iran to temporarily limit its nuclear program, in return for an irreversible lifting of sanctions which will enable Tehran to further fuel conflicts throughout the region. Even if Iran keeps to the deal, US President Barack Obama himself admitted it could reach nuclear “breakout capacity” in 13 years’ time.

The American Jewish community is split over whether to back the landmark accord, though most oppose it.

Extremist liberal group J Street supports it, but the American Jewish Committee, a leading Jewish advocacy organization, has come out opposed, as has the influential American Israel Public Affairs Committee.

Among the rabbis who signed the congressional letter, 49 are from New York, the state represented by senior Senate Democrat Chuck Schumer, who earlier this month announced he will oppose the accord when it comes up in Congress in September.

On Tuesday another influential Democrat, Senator Robert Menendez, gives a speech on the Iran nuclear accord and will announce whether he will vote for or against it.  

Congress is expected to pass a resolution opposing the deal in September.

President Barack Obama will veto that measure, but Congress could override such a veto – and kill the Iran deal – with a two-thirds majority in both chambers.