Such a plan, under which the United States could free up Iran’s frozen overseas assets in installments, would avoid the political and diplomatic risks of repealing the sanctions, which had been agreed to by a diverse coalition of countries, the official said Thursday on condition of anonymity.

It would also give President Barack Obama the flexibility to respond to Iranian offers that emerge from the negotiations without unraveling the global sanctions regime the administration has spent years cobbling together.

The official likened the plan, which is still being debated inside the White House and the State Department, to opening and closing a financial spigot.

While the two days of talks in Geneva this week did not produce an eye-catching breakthrough, Iranian officials were candid and substantive, officials said, particularly in direct negotiations between Iranian diplomats and the senior American representative, Wendy R. Sherman.

Now, though, the administration faces a complex calculation on the future of the sanctions, which have been crucial in bringing the Iranians back to the bargaining table. Administration officials said they would urge the Senate to hold off on voting on a new bill to strangle Iran’s oil exports further until after the next round of talks on Nov. 7.

Still, the positive tone of the talks — a senior American diplomat who took part characterized them as “intense, detailed, straightforward, candid conversations” — has prompted new thinking in Washington about how to ease the pressure on Tehran, if not immediately, then down the road.

The proposal on freeing up funds has been championed by Mark Dubowitz, executive director of the Foundation for Defense of Democracies, a public policy institute known for its hawkish views on Iran. “My biggest concern is that if the administration takes out a brick from the sanctions regime, you won’t be able to put it back together,” Dubowitz said. He called the plan “a way to provide non-sanctions financial relief to give the administration flexibility during the negotiations.”

If Iran refused to make concessions, the United States, he said, could pair its offer to free Iranian money with a new sanction that would immediately freeze all of its foreign exchange reserves by cutting off from the American financial system any bank that gives Iran use of those funds.

NTJ/BA