NEW YORK (JTA) – The U.S. Conservative, Reform and Reconstructionist movements are warning that a proposed Israeli conversion bill is “disastrous to the unity of the Jewish people.”

Knesset members from the Yisrael Beiteinu party were in the United States this week trying to marshal support for a bill that would change the conversion process in Israel. 

While the bill’s proponents say it would make it easier for the estimated 350,000 to 400,000 non-Jewish Israelis from the Russian-speaking immigrant community to convert to Judaism and marry in Israel, critics say the bill threatens to alter the Law of Return and consolidate conversion power in the hands of the Chief Rabbinate.

That “could have devastating effects on the relationship between Israeli and Diaspora Jewry,” the three main non-Orthodox Jewish movements in the United States said in a joint statement. “Such concentration of powers in favor of ultra-Orthodox Jewry effectively negates the roles of the non-Orthodox movements both within Israel and abroad, sending the message that only the Orthodox have a place within our homeland.”

The statement said the legislation, which is being promoted by Knesset member David Rotem, would revive the destructive debate over who is a Jew and turn the clock back on 20 years of accomplishments in the Israeli Supreme Court asserting the legitimacy of non-Orthodox movements.

“The bill mentions no alternative method of conversion via non-Orthodox streams,” the statement said. “We – and more importantly, our Israeli colleagues and their lawyers – believe that this language, if adopted as written, would further marginalize and hamper the Masorti and Reform movements in Israel. This would be a tragic consequence as we offer vibrant religious alternatives to a nation of Jews religiously alienated by the increasingly extreme positions of a minority religious establishment.”

In an interview this week with JTA, Rotem said the non-Orthodox religious streams in the United States should not be anxious about the bill.

“I want them not to worry it’s going to harm them,” Rotem said. “This law doesn’t deal with conversions done abroad. We have to solve an internal Israeli problem.”