Major world powers inked an interim accord with Iran on Nov. 24 to offer Tehran modest sanctions relief in return for Iran taking steps to limit its uranium enrichment activities. The deal called for negotiation of a full agreement within a year.
In testimony to the Senate Foreign Relations Committee on Tuesday, US lead negotiator Wendy Sherman, and top sanctions official David Cohen, dismissed reports that Iran's economy was improving.
Some members of Congress have slammed the deal, arguing it does not renounce a right for Iran to enrich uranium, while allowing for some relief from the sanctions.
Sherman said that while the nuclear deal was “not perfect,” it was a “first step” in securing a comprehensive agreement.
The US top negotiator also said that the White House would be willing to accept a “small, limited enrichment program.”
The contentious hearing comes as 59 senators have signed onto new sanctions that would set in if a final deal is not signed in six months or if it does not meet their demands.
However, support for the bill has lost steam as Senate Democratic leaders have sided with the administration in favor of waiting for the negotiations to play out.
President Obama has said he would veto the bill if it landed on his desk as talks still progress.
Senator Robert Menendez, the committee chairman, testified that the Obama administration has “placed our incredibly effective international sanctions regime on the line without clearly defining the parameters of what we expect in a final agreement.”
"At the end of the day, any final deal must require Iran to dismantle large portions of its nuclear infrastructure," the senator said. "Any final deal must address Iran's advanced centrifuge research and development activities that allow it to more quickly and more efficiently enrich uranium."
“It’s not simply about passing sanctions,” Menendez added. “It’s about the time frame necessary to have them be effective.”