Senator McConnell: Any Iran nuclear deal has tough road in US Congress
US House Speaker John Boehner (L) and Senate Majority Leader Mitch McConnell (C) host a rare joint press conference on January 15, 2015, along with first-term Senator Joni Ernst, at a Republican retreat in Hershey, Pennsylvania (AFP Photo/Michael Mathes)

The top Republican in the U.S. Senate on Sunday cast doubt on whether President Barack Obama will be able to win approval in Congress for any nuclear deal now under negotiation with Iran.

"I think it's going to be a very hard sell, if it's completed, in Congress," Senate Majority Leader Mitch McConnell said during an interview on the "Fox News Sunday" broadcast. "We already know it's going to leave Iran as a threshold nuclear state."

(Reporting by Richard Cowan; Editing by Robin Pomeroy)