Iran and the United States are set to begin a fifth round of high-stakes nuclear talks in Rome on Friday amid growing skepticism in Tehran about the chances of a deal as Washington hardens its position.

ROME—Iran and the U.S. are aiming to set the parameters for a new deal on Tehran’s nuclear program while leaving important details still to be negotiated, people familiar with the talks said. Seeking a political framework on Iran’s nuclear program would in some ways mirror a 2013 interim agreement that preceded the 2015 nuclear deal Iran reached with the Obama administration.

DUBAI (Reuters) -Iranian and U.S. negotiators will resume talks on Friday in Rome to resolve a decades-long dispute over Tehran's nuclear ambitions, despite Iran's supreme leader warning that clinching a new deal might be insurmountable amid clashing red lines.