"After consulting with EU High Representative Ashton and the negotiating team on the ground, Secretary Kerry will travel to Geneva later today with the goal of continuing to help narrow the differences and move closer to an agreement."
A top Iranian diplomat said Thursday the West must affirm Tehran's right to enrich uranium or there's no deal.
"If this element is not in the text, it is unacceptable to us. Without that, there will be no agreement," Iranian Deputy Foreign Minister Abbas Araqchi told reporters in Geneva, ahead of Friday's final scheduled day of talks between Iran and the five permanent members of the U.N. Security Council plus Germany, a group known as the P5-plus-1.
The Obama administration argues the U.N. Non-Proliferation Treaty doesn't recognize every country's right to produce nuclear fuel, even though it says all nations have a right to civilian nuclear technologies.
The 1968 accord, signed by 190 countries, guarantees a nation's right to a peaceful nuclear program without specifically mentioning enrichment.
The P5-plus-1 and Iranian diplomats are meeting in a third round of talks to try to reach a deal that would give Tehran economic-sanctions relief in exchange for reining in some activities the West suspects are aimed at making a nuclear weapon. Iran insists its nuclear program is strictly for production of energy and medical research.
The current round was scheduled to end Friday, but diplomats said it might be extended into the weekend, either in the hope of reaching an interim accord or to decide to meet again.
France called on the international community to maintain its resolve over the language of a proposed interim deal that would effectively halt Iran's uranium enrichment and plutonium programs.
"This agreement can only be possible based on firmness," Foreign Minister Laurent Fabius told France 2 television. "For now the Iranians have not been able to accept the position of the six. I hope they will accept it."
The United States, Britain, France, China, Russia and Germany would then agree to relieve some financial sanctions against Iran for six months, during which time the parties would attempt to forge a comprehensive, permanent agreement.
Failure to reach a final deal in that time would lead to the return of full sanctions.
"The P5-plus-1 remains entirely united in our proposal, and we are focused on doing everything we can to conclude a first step agreement with Iran," Psaki said Thursday.
"Our negotiators are making progress, but as we all know, these issues are complicated and require time to hash out," she said.
Iran's insistence on having the P5-plus-1 affirm Iran's claim it has a "right" to enrich uranium followed a speech by Iranian Supreme Leader Ayatollah Ali Khamenei, who was adamant about the point.
Three days earlier, Iranian Foreign Minister Javad Zarif was quoted by the semiofficial Iranian Students News Agency as saying Tehran saw no "necessity" for the P5-plus-1 to recognize the right since it was asserted and preserved in the Non-Proliferation Treaty.
As the talks appeared to stumble, Senate Majority Leader Harry Reid, D-Nev., threw his support behind a new sanctions bill if they fail.
"We all strongly support those negotiations and hope they will succeed, and want them to produce the strongest possible agreement," said Reid, who controls whether bills get a vote in the upper chamber.
"However, Mr. President, we're also aware of the possibility that the Iranians could keep the negotiations from succeeding," he said in a speech on the Senate floor.
"I hope that won't happen," Reid said. "But the Senate must be prepared to move forward with a new bipartisan Iran sanctions bill when the Senate returns after the Thanksgiving recess. I'm committed to do just that."
He said he would "support a bill that would broaden the scope of our current petroleum sanctions, place limitations on trade with strategic sectors of the Iranian economy that support its nuclear ambitions, as well as pursue those who divert goods to Iran."
He said the bill could be approved next month.
The White House has urged lawmakers to delay any new sanctions to give time for the diplomatic process.
Psaki thanked Reid for waiting, but said any indication Washington wasn't committed to diplomacy was "unhelpful."