Senate Democrats delivered President Barack Obama a victory when they blocked a resolution of disapproval against the deal on Thursday.
The procedural vote, 58-42, fell short of the 60 votes needed to advance to a final vote and came after a lengthy floor debate — the culmination of acrimonious and often partisan back and forth following the agreement between the U.S., Iran and five world powers was struck.
The agreement involves limiting Iran's nuclear production for 10 years and Tehran's access to nuclear fuel and equipment for 15 years in return for hundreds of millions of dollars in sanctions relief.
Over the past several months, the White House has fiercely defended the Iran nuclear deal in tough congressional hearings, speeches and interviews with the press against tough questions from skeptics. Throughout August, members of Congress have announced where they stand on the deal, which was sent to Congress by President Barack Obama back in July.
The vote heads off a tense veto showdown between Congress and the White House and helps the deal move forward.
Meanwhile, House Republicans earlier in the day and week had vowed to fight on.
Instead of simply voting on a resolution of disapproval which was the original plan, on Wednesday the House GOP leadership came under fire from conservatives who said that the clock for when Congress received the Iran deal from the administration has not yet started.
Those conservatives, including Sen. Ted Cruz, R-Texas, a Republican presidential candidate, said this makes the deal invalid and have called on party leadership to fight.
House Speaker John Boehner, R-Ohio, has pledged to do exactly that.
“This debate is far from over,” Boehner said during his weekly press conference. “And, frankly, it is just the beginning. This is a bad deal with decades long consequences for the security of the American people our allies. We will use every tool at our disposal to stop, slow and delay this agreement from being fully implemented.”