Already, the Barack Obama administration and some leading Republican senators are using the Israeli internal disagreement to undermine support for the bill, authored by Republican Mark Kirk and Democrat Robert Menendez, which would enact new sanctions if current negotiations falter.

Bob Corker, chairman of the Senate Foreign Relations Committee — supported by Republican Senators Lindsay Graham and John McCain — is pushing for his own legislation on the Iran nuclear deal, which doesn’t contain sanctions but would require that the Senate vote on any pact that is agreed upon in Geneva. The White House is opposed to both the Kirk-Menendez bill and the Corker bill; it doesn’t want Congress to meddle at all in the delicate multilateral diplomacy with Iran.

Israeli intelligence officials have been briefing both Obama administration officials and visiting U.S. senators about their concerns on the Kirk-Menendez bill, which would increase sanctions on Iran only if the Iranian government can’t strike a deal with the so-called P5+1 countries by a June 30 deadline or fails to live up to its commitments. Meanwhile, the Israeli prime minister’s office has been supporting the Kirk-Menendez bill, as does the American Israel Public Affairs Committee, ahead of what will be a major foreign policy confrontation between the executive and legislative branches of the U.S. government in coming weeks.