The text of a proposed nuclear deal between Iran and world powers, distributed by the European Union to negotiators, is in limbo while the head of Iran’s delegation consults with the Tehran government over its terms, according to U.S. and foreign officials familiar with the talks being held in Vienna.“There are papers and text that have been shared,” a senior State Department official said Friday. “I think enough is on the table now that Iran has a very clear sense of what it stands to gain and what it stands to lose” in returning to compliance with the 2015 agreement that limited its nuclear program in exchange for sanctions relief.

Chief Iranian negotiator Ali Bagheri Kani left Vienna late Wednesday following what several officials familiar with the text said were indications the Iranian team found it largely acceptable. Since then, the Iranian government, which has been publicly outspoken about its positions since the talks began last year, has been silent on the subject.

The E.U. has coordinated the talks between Iran and four of the five permanent members of the United Nations Security Council — Britain, France, Russia and China — plus Germany. All were original signers of the deal, along with the United States. U.S. withdrawal from the agreement in 2018, and the reimposition and expansion of harsh economic sanctions by the Trump administration led Iran to rapidly expand its nuclear activities far beyond the bounds of the agreement. Iran has refused to meet directly with the United States, which is negotiating through the European delegations.

The apparent endgame in the Iran talks arrives as the United States is locked in confrontation with Russia over Ukraine and has shut down most communication with Moscow. U.S. officials throughout the talks have said that both Russia and China have played constructive roles, and the State Department official said that has not changed.

Those sitting across the table from Iran initially came together because of a “common interest that Iran couldn’t acquire a nuclear bomb” and a desire to resolve the situation “without confrontation,” the official said. “We’re not doing this as a favor to Russia; they’re not doing it as a favor to us,” the official said. “On this issue … we appear to have a common interest.”

While there was “significant progress in the last week or two” of negotiations, “It’s important to note that very serious issues remain,” the official said. “Issues left for last are left for last for a reason … [and] it’s wrong to say right now that they will be resolved, particularly since we have very little time to resolve them, given the pace of Iran’s nuclear advances.”