Secretary of State John Kerry met with his Iranian counterpart on Wednesday night for what diplomats said could be a series of pivotal sessions as the United States and its negotiating partners sought to secure a preliminary accord to limit Iran’s nuclear program.
Germany’s foreign minister, Frank-Walter Steinmeier, said before the meetings that the Iranians were expected to present “new recommendations” on how to bridge the gaps that have been holding up the accord.
As the talks appeared headed toward a potential moment of decision, Mr. Kerry and Mr. Steinmeier decided to extend their stay here another day.
In another sign that the talks were intensifying, Laurent Fabius, France’s foreign minister, was flying here from Paris, Agence France-Presse reported.
Marie Harf, a State Department spokeswoman, confirmed that Mr. Kerry was staying on to give the diplomacy another try.
“We continue to make progress but have not reached a political understanding,” she said. “Therefore, Secretary Kerry will remain in Lausanne until at least Thursday morning to continue the negotiations.”
Mr. Kerry met one-on-one with Mohammad Javad Zarif, Iran’s foreign minister, on Wednesday, followed by larger sessions that included the two foreign ministers and a senior European Union diplomat, Helga Schmid.
The talks have been snagged by disputes over what sort of research should be permitted on advanced centrifuges to enrich uranium and the pace of sanctions relief, especially those imposed by the United Nations, among other issues. Another issue in dispute has been whether a preliminary accord should spell out specific limits, as the United States has insisted, or be more general, as Iran has preferred.
Heading toward the meetings, Mr. Zarif repeated a often used talking point, insisted that Iran was showing flexibility and that was up to United States and its partners to reciprocated.
“Our friends need decide whether they want to be with Iran based on respect or whether they want to continue based on pressure,” Mr. Zarif said. “They have tested the other one; it is high time to test this one”
Before the talks were extended, the Obama administration had been struggling to meet what was essentially a self-imposed deadline for an initial accord that would outline the main elements of an agreement.
The administration’s calculation is that a preliminary accord would lay the foundation for a comprehensive agreement to be completed by the end of June.
It would also, the White House hopes, let the administration make a stronger case against American lawmakers who have been pressing for additional economic sanctions on Iran.
But lawmakers are not scheduled to return from their recess until mid-April. The Obama administration’s hopes of winning its battle with Congress will depend more on what concrete agreements are reached here, and what issues are put off for further talks with the Iranians, than on whether a preliminary accord is settled on Wednesday or over the next week or two.
Apart from the complexity of the nuclear issues, the talks have been complicated by clashing agendas for the United States and Iran.
The Obama administration, for example, has been eager to impose specific limits on Iran’s nuclear program as soon as possible to buttress its argument to Congress. It also wants any sanctions relief to be carried out in phases to help ensure that Iran meets its obligations.
Iran’s negotiators, however, have demanded that sanctions relief be provided up front, and they have resisted the formalization of stringent limits in a preliminary accord.
Iran’s deputy foreign minister, Abbas Araqchi, said on Wednesday that he expected Iran and other negotiators to issue “a press statement” later in the day that would “announce progress in the negotiations.”
“It will announce that we have managed to find solutions for key issues,” he told Iranian television. “Then we will start to write down the solutions.”
Sergey V. Lavrov, Russia’s foreign minister, told reporters on Tuesday that a deal was virtually in hand and that a general understanding had been reached on “all key aspects.”
But Mr. Lavrov made similarly upbeat comments on Monday before the State Department announced that the talks had been extended and that “several difficult issues” remained.
