The top Republican in the U.S. Senate cast doubt on Sunday on whether President Barack Obama would be able to win approval in Congress for any nuclear deal with Iran, and some Democrats also expressed reservations. “I think it’s going to be a very hard sell, if it’s completed, in Congress,” Senate Majority Leader Mitch McConnell told “Fox News Sunday”. “We already know it’s going to leave Iran as a threshold nuclear state.” The U.S. Congress could play a key role in the future of any deal to curb Iran’s nuclear program, with negotiations reaching a critical juncture in Vienna on Sunday. Obama can enter a deal with Iran, which Congress would review. If the review went against him, Obama could veto the disapproval legislation. Congress could then try to reverse his veto, which is difficult. But if it succeeded, its disapproval would take away Obama’s ability to temporarily […]