A movement to levy more sanctions to cripple the Iranian economy had been moving fast in Congress. But on Tuesday, Sen. Bob Menendez, a Democrat who co-authored the measure with Sen. Mark Kirk, a Republican, and nine other Democrats told Obama in a letter that they wouldn't push the bill at least until the end of March.

The bill would not impose any new sanctions during the remaining timeline for negotiations. It says that if there is no deal by July 6, the sanctions that were eased during negotiations would be reinstated. After that, sanctions would be stepped up every month.

The committee voted to amend the bill to include a statement that Israel, an archenemy of Iran, has a right to defend itself. Other amendments to the bill that passed allow Congress to vote on any deal approved with Iran; beef up reporting requirements for verifying that Iran is complying with any agreement reached and task the Treasury Department to report on the economic impact of sanctions relief on Iran.

Last week, House Speaker John Boehner fueled the rising friction between Congress and the White House by announcing that he had invited Israeli Prime Minister Benjamin Netanyahu to address Congress March 3 and push for new sanctions. A group of Democrats is trying to get Boehner to postpone the address.