Secretary of State Antony Blinken is "building a dedicated team" to address Washington's relations with Iran, to be led by Malley, a State Department official said Friday.

Malley, a childhood friend of Blinken, has been serving as head of the International Crisis Group, an independent non-governmental organization focused on conflict resolution.

Before that, he was one of the chief negotiators on the 2015 nuclear deal reached by Iran and world powers, under which Tehran was promised economic relief for major curbs in its contested nuclear program.

Malley "brings to the position a track record of success negotiating constraints on Iran's nuclear program," the State Department official said.

"The Secretary is confident he and his team will be able to do that once again."

The deal was reached under Barack Obama, when President Joe Biden was his number two.

But in 2018, Donald Trump unilaterally withdrew the United States from the accord, which was also signed by Britain, China, France, Germany and Russia.

The Trump administration deemed the deal not tough enough, and felt it should have also covered what it saw as Iran's "destabilizing" activities in the Middle East. It slapped tough sanctions on Tehran.

This week, Blinken confirmed the new US administration's intention to rejoin the accord -- once Tehran meets its commitments.

Iran responded to the tough Trump-era sanctions by reducing its compliance with the deal, formally known as the Joint Comprehensive Plan of Action (JCPOA). It wants Washington to make the first move.

Before he was even named to the post, rumors of Malley's nomination prompted sharp criticism from anti-Iran hawks on the political right.

"It's deeply troubling that President Biden would consider appointing Rob Malley to direct Iran policy," Republican Senator Tom Cotton tweeted last week.

"Malley has a long track record of sympathy for the Iranian regime & animus towards Israel. The ayatollahs wouldn't believe their luck if he is selected."