Bradley Klapper ?and Deb Riechmann

WASHINGTON: The Obama administration moved on two fronts Monday to advance its nuclear diplomacy with Iran, with talks between top U.S. and Iranian diplomats and an aggressive effort to sell the emerging deal to skeptical American lawmakers and constituencies.

U.S. Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif met at the residence of Iran’s ambassador to the United Nations in New York for the first time since April 2, when world powers and Iran sealed a framework agreement that would limit Iran’s ability to build a nuclear weapon. They now have little more than two months to meet their own June 30 deadline for a comprehensive accord.

Neither man spoke to reporters as the meeting got underway, but earlier Kerry told a U.N. conference on nuclear non-proliferation that a deal would make the world a safer place. “I want you to know the hard work is far from over and some key issues remain unresolved,” he said. “But we are, in fact, closer than ever to the good comprehensive deal that we have been seeking. And if we can get there, the entire world will be safer.”

In Washington, lead U.S. negotiator Wendy Sherman told a conference of reform Jews that diplomatic collapse would leave Iran perilously close to nuclear weapons capacity. Energy Secretary Ernest Moniz said a final agreement would in some ways be tougher than what the U.S. has outlined thus far.

All the activity was taking place before the Senate begins debate Tuesday over empowering Congress to review and possibly reject any nuclear pact. Republican presidential candidates are lining up to oppose any deal with a government the U.S. considers the world’s leading state sponsor of terrorism and to show their support for Israel.

Sen. Marco Rubio of Florida wants to require Iran’s leaders to publicly accept Israel’s right to exist, a nearly impossible mandate. Sen. Ted Cruz of Texas hopes to put the onus on advocates to win congressional approval of a deal.

But even as the legislation moves forward, House Speaker John Boehner privately acknowledged to a gathering of the Republican Jewish Coalition over the weekend that his party doesn’t command enough votes to override a presidential veto of any resolution disapproving of an Iran deal, BloombergView reported.