World powers will hold a virtual meeting with Iran on Friday to discuss “the prospect of a possible return of the United States” to the Iran nuclear deal, the European Union said.

The six countries still party to the deal since the United States withdrew nearly three years ago — Britain, France, Germany, Russia, China and Iran — will attend the E.U.-chaired meeting, according to a statement by the European body.

The Biden administration welcomed what it called a “positive step,” signaling a possible breakthrough in the months-long stalemate between the United States and Iran over the conditions for a U.S. return to the agreement.

“We have been clear for weeks now that we are ready to pursue a return to compliance with our JCPOA commitments, consistent with Iran also doing the same,” State Department spokesman Ned Price told reporters. The agreement is officially known as the Joint Comprehensive Plan of Action.

“We took note of the Europeans’ announcement today as a positive step, especially if it moves the ball forward,” he said.

President Donald Trump withdrew from the 2015 accord, which he consistently criticized as a “bad deal.” He reimposed harsh economic sanctions on Iran that had been lifted as part of the agreement, and added more than a thousand new measures. In response, Iran eventually began enriching uranium to levels that the deal had prohibited.

The United States charged, and Iran denied, that its goal was to construct a nuclear weapon.

President Biden campaigned on a promise to rejoin the accord, saying that it had successfully constrained Iran’s nuclear ambitions. The administration now estimates that Iran’s “breakout time” — the amount of time needed to produce enough fissile material for one nuclear device — has been reduced from more than a year, under the agreement, to only a few months.

But attempts earlier this year to negotiate a U.S. return to the accord repeatedly faltered as the United States and Iran each insisted the other take the first steps. The administration said it would lift Trump-imposed sanctions if Iran returned to compliance with limits on uranium enrichment and full international monitoring. Iran, noting that it was the United States that quit the accord, said it would return to the terms of the deal once the sanctions were removed.

The Iranians also have said they had no interest in Biden-proposed “follow-on” talks about Iran’s ballistic missile program, proxy wars in the region and alleged terrorism sponsorship.

Both the United States and Iran have to deal with domestic political pressures for and against agreement. Iran is gearing up for elections in June that will center in large part on the nuclear deal.

Iran rejected an E.U. proposal in late February to gather the original parties to the agreement — including the United States — saying that it first wanted a clear-cut agenda.

Since then, the administration has made clear that it would participate in “indirect” talks, through the Europeans. Britain, France and Germany, which maintain embassies in Tehran, have served as conduits as the two sides proposed sequential, simultaneous steps to bring them into mutual compliance.

“Working closely with our [European] partners as well as Moscow and Beijing, we are determined to find a diplomatic solution that allows Iran to resume respect for its nuclear commitments and the United States to return to the agreement as swiftly as possible. We are engaged in ongoing discussions with Washington and Tehran in that regard,” French Foreign Ministry spokeswoman Agnes von der Muhll said Thursday.