Republican Sen. Bob Corker of Tennessee, who attended the White House meeting, said Obama asked lawmakers to pause for "a period of time." Corker did not specify how long the president asked lawmakers to wait.
Corker said some lawmakers want to be able to at least announce new sanctions proposals in the coming days. But he said there will not be any sanctions amendments added before Thanksgiving to an annual defense bill, which could be the main vehicle for new imposing economic penalties.
White House spokesman Jay Carney said Obama told the senators that if there's not an initial agreement, Iran will keep making progress on its enrichment program. He said new sanctions would be most effective as a consequence for Iran refusing to accept a deal or forsaking its commitments under an agreement.
Undeterred, a group of Republican senators led by Sen. Mark Kirk, R-Ill., pushed ahead with a new round of sanctions, circulating a letter to other senators asking for support for adding the sanctions to a defense bill. But the amendment had little chance of coming up for a vote before the Senate's Thanksgiving recess, leaving time for a deal to be reached before new sanctions would be finalized.
Separately, in a letter to Secretary of State John Kerry after the meeting, six senators from both parties cast doubt on the budding deal, urging the Obama administration not to accept an agreement that would be overly generous to Iran or insufficiently tough on its nuclear program. Among those signing the letter were Obama allies Sen. Chuck Schumer, D-N.Y., and Sen. Bob Menendez, D-N.J., chairman of the Senate Foreign Relations Committee.
In the letter, the senators cited specific concerns about nuclear activities Iran would continue to be allowed to conduct, such as enriching uranium at certain levels and maintaining its current number of centrifuges. The senators also said some estimates put the value of the sanctions relief in the deal at up to $10 billion.
"We regard this as a major concession on our part that would not be justified by the concessions the Iranian regime would be required to make in return," the senators wrote. "If we are reducing sanctions, Iran should be reducing its nuclear capabilities."
Obama convened the meeting one day before the U.S. and five other world powers resume talks with Iran in Geneva.