US Secretary of State John Kerry warned Congress against imposing new sanctions against Iran. Kerry said fresh sanctions could destroy diplomatic efforts to rein in Tehran's nuclear program.
Kerry asked a US lawmakers on Wednesday to refrain from passing new sanctions or risk imperiling delicate nuclear talks.
"We put these sanctions in place in order to be able to put us in the strongest position possible to be able to negotiate," the US Secretary of State told reporters ahead of a closed-door meeting with members of a Senate Banking Committee.
"We now are negotiating, and the risk is that if Congress were to unilaterally move to raise sanctions, it could break faith with those negotiations and actually stop them and break them apart," Kerry added.
The five permanent members of the UN Security Council and Germany, known as the P5+1, are engaged in ongoing high-level talks with Iran aimed at reaching an interim deal to halt parts of Tehran's nuclear program - in exchange for the suspension of some sanctions. While Iran asserts its atomic program is for peaceful purposes only, the coalition fears it could be seeking to develop nuclear weapons.
The latest round of talks in Geneva last week failed to yield a deal, however, after Iran rejected a proposal presented by the US, Britain, France, China, Russia and Germany.
The House of Representatives has already passed legislation that toughens sanctions on Iran. With the Senate committee also considering new sanctions legislation, Kerry and Vice President Joe Biden were tasked with making the case for diplomacy before talks resume on November 20.
"What we are asking everyone to do is calm down, look hard at what can be achieved and what the realities are," Kerry said.
"Let's give them a few weeks, see if it works," he said, adding that there was "unity" among the six powers negotiating with the Islamic republic.
"If this doesn't work, we reserve the right to dial back the sanctions." In that event Kerry added he would return to Capitol Hill "asking for increased sanctions. And we always reserve the military option."
Kerry's request faced sharp criticism from members of Congress on Wednesday, many of whom are wary of yielding any ground to Iran.
"The Iranian regime hasn't paused its nuclear program," said Ed Royce, a Republican and House Foreign Affairs Committee chairman. "Why should we pause our sanctions efforts as the administration is pressuring Congress to do?"
Fellow Republican and member of the Senate Banking Committee Bob Corker said Kerry made an "emotional appeal" but did not provide much-sought-after details of the proposal that Washington and other western powers put on the table for Iran.
"I was very disappointed in the presentation. It lacked content," Corker said.
Democrat Tim Johnson, the Senate Banking Committee's chairman, merely said he was "undecided" about whether to proceed with new sanctions.
Since Iranian President Hassan Rouhani took office in July, the Obama administration has increasingly focused on diplomatic efforts to end the decades-long standoff . The new president has indicated a desire to ease Iran's international isolation.
The new diplomatic focus has not only drawn criticism among Democrats and Republicans on Capitol Hill. It has also been met with concern by US allies Israel and Saudi Arabia.
Last week Israeli Prime Minister Benjamin Netanyahu accused Kerry of offering Iran "the deal of the century," adding that Israel would not be bound by any agreement with Tehran.