VIENNA — U.S. Secretary of State John Kerry decided today to pull back from nuclear talks in Vienna, leaving Iran’s foreign minister to ponder an apparent new proposal meant to bridge differences standing in the way of a deal with less than four days to deadline.

Iranian officials and media initially said Foreign Minister Mohammad Javad Zarif also was departing today, to Tehran to consult after meeting with Kerry earlier in the day. But the official IRNA news agency later quoted an unidentified Iranian nuclear negotiator in Vienna as saying Zarif was staying “and the talks will continue.”

Kerry was heading for Paris. A U.S. statement said his “future travel schedule is still being finalized, and we have not yet determined when he will return to Vienna.” That suggested that he was waiting to see whether there was enough momentum to warrant him rejoining the talks.

Expectations are growing that the Monday deadline for a full deal will be missed because of differences on how much Iran needs to reduce the size and scope of key nuclear programs. Both the Iranians and the six world powers negotiating with them must soon decide whether to go beyond Monday or adjourn to a later date. They may also opt to end negotiations, but that is unlikely.