TEHRAN — Until this summer, Mohammad Javad Zarif, one of Iran’s most accomplished diplomats, was an outcast, exiled from the government by ultraconservatives for working too closely with the West. Rather than presenting the Iranian case to the world, as he had done so effectively throughout a 35-year diplomatic career, he was spending his days teaching at the Foreign Ministry’s training center on a quiet, leafy campus in North Tehran.

That changed with the election of the moderate president, Hassan Rouhani, in June. Now, Mr. Zarif is the country’s new foreign minister and seems virtually certain to lead Iran’s delegation in nuclear negotiations with the West — further indications, analysts say, that Mr. Rouhani is serious about reducing tensions with the United States and other Western countries.

“Mr. Zarif is the new face of a new policy,” said Davoud Hermidas-Bavand, a professor of international relations at Allameh Tabatabaei University in Tehran, who knows Mr. Zarif personally. “Our former foreign policy obviously did not yield any results and was clearly doomed. We need to revise our former methods and soften our stances in order to find a solution to the nuclear problem and reduce the sanctions.”

Previous negotiations over Iran’s nuclear program have broken down on the West’s insistence that the country’s government first stop enriching uranium, which world powers suspect is a first step to developing nuclear weapons. The Iranians have maintained just as steadfastly that they have the right to enrich uranium for fuel to power reactors and for other peaceful uses. Now, this diplomatic logjam may be giving way, analysts say.