"We certainly would want, and expect, that if a deal is completed, it will include tangible, specific commitments that have been made by the Iranians," White House press secretary Josh Earnest said.
His comments followed a New York Times report that Iran is resisting a formal "framework" agreement and preferred a more general statement of "understanding" followed by a final accord in June.
World power negotiations with Iran are entering a crucial final week in Switzerland before a March 31 deadline for an agreement that would block its path to obtaining a nuclear weapon in return for sanctions relief.
US Secretary of State John Kerry departed Wednesday for talks with Iranian Foreign Minister Mohammad Javad Zarif.
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Earnest said the Iranians were making "certain commitments" in the negotiations on its nuclear program and said there would a "process" for hammering out the details of those commitment.
"But the president was clear that the kinds of commitments that we seek from the Iranians are the kinds of things that we would be able to show to members of Congress and show publicly, to share with our allies, including Israel, about what kinds of commitments Iran has made," he said.