Banking Committee Chairman Tim Johnson, D-S.D., whose panel oversees sanctions legislation in the Senate, said the administration made a strong case to hold off on congressional action, and he was therefore inclined not to move sanctions legislation forward in his committee, at least for now.
His statement came after Kerry pleaded with House lawmakers to give breathing room to the international diplomatic efforts to curb Iran's nuclear program.
The Obama administration opposes even a bill that defers new sanctions for six months, imposing them only if Iran fails to adhere to strict limits on its program, Kerry told the House Foreign Affairs Committee.
But Kerry said he would immediately appeal to Congress for tougher sanctions if the negotiations toward a comprehensive nuclear accord fall short.
"We are committed to asking you for additional sanctions if we fail," Kerry told lawmakers Tuesday. "We will need them."
Kerry spoke a day before huddling with senators Wednesday for a classified briefing on the interim deal reached between Iran and Western powers in Geneva, Switzerland, Nov. 24.
The afternoon briefing, in what the Washington Post said would be a secure location on Capitol Hill, will also include Treasury Secretary Jack Lew, Politico reported.
Kerry and Lew are expected to lay out the interim deal's status, Politico said.
Top Treasury and State Department officials are to testify before the Senate Banking Committee in open session Thursday.
Johnson, whose committee has been debating whether to push ahead with new sanctions to pressure Tehran to roll back its nuclear program, said he would not back new measures for now, even though other prominent Democrats, including Sen. Chuck Schumer of New York, supported tough, new sanctions with deferred imposition.
"The president and Secretary Kerry have made a strong case for a pause in congressional action on new Iran sanctions, so I am inclined to support their request and hold off on committee action for now. I'll have more to say on this at Thursday's Banking Committee hearing," Johnson said in a statement.
Many lawmakers are not satisfied with the Geneva deal and have said applying further pressure on the government of President Hassan Rouhani is the only way to extract concessions that would ensure Iran never develops nuclear weapons.
Iran insists its nuclear is solely for peaceful purposes.
Iranian Foreign Minister Javad Zarif told Time magazine in an interview published Monday any new sanctions would kill a comprehensive deal.
New sanctions would mean "the entire deal is dead," he said when asked what would happen if Congress imposed new sanctions, even if they didn't go into effect for six months.
"We do not like to negotiate under duress," Zarif said. "And if Congress adopts sanctions, it shows lack of seriousness and lack of a desire to achieve a resolution on the part of the United States. I know the domestic complications and various issues inside the United States, but for me that is no justification."
Some experts cited by the New York Times said they thought Zarif was posturing in threatening to break off negotiations.
While the Obama administration wants Congress to wait before deciding whether to impose more sanctions, the administration is preparing to blacklist several Iranian individuals for violations unrelated to the nuclear program, the Times said.
The goal of the blacklisting is to show Congress the administration is keeping pressure on Iran over human rights and terrorism during the nuclear-program talks, the Times said.