Republican Senate Majority Leader Mitch McConnell warned that President Barack Obama faces a very big hurdle if the Iran nuclear deal is reached by Monday’s deadline.
The Kentucky senator on Sunday said it is going to be a “very hard sell” to get Congress to agree to the terms of the deal, adding that he believes his Democratic colleagues will have similar concerns.
"I know there will be a strong pull not to go against the president on something as important as this is to him. But I hope there will be enough Democrats willing to look at this objectively and look at the facts,” McConnell said on "Fox News Sunday."
McConnell’s remarks come hours before a looming Monday deadline to reach a nuclear deal. A provisional deal could be reached as early as Sunday, according to The Associated Press.
Secretary of State John Kerry said he is “hopeful” that the deal will be reached between Iran and the U.S., Britain, Germany, France, Russia and China, telling reporters "I think we're getting to some real decisions."
MSNBC's Andrea Mitchell tweeted that major issues need to be resolved tonight, according to a senior U.S. official.
McConnell said there are still questions that remain unclear, including whether Iran will "reveal their past research and development," and probing "what have they done on the past on this subject? Is it verifiable? Will we be able to look at all of their military bases?"
McConnell said applying tougher sanctions is the best way for the six major world powers and Iran to decide how to handle the nuclear program.
If a deal is reached, Iran will have to slow down or completely halt its nuclear research. Then, once the deal reaches Congress, they will have 60 days to review, and either approve or reject it. If they move to reject the deal, it would create the same outcome as the deal not being reached in the first place – allowing Iran to resume its nuclear expansion.
This historic deal has already been extended two weeks past its initial June 30 deadline.
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Republican House Speaker John Boehner on Sunday urged Obama to walk away from the talks. "No deal is better than a bad deal," Boehner said on CBS’s “Face the Nation.”
“From everything that's leaked from these negotiations, the administration's backed away from almost all of the guidelines that they set up for themselves. And I don't want to see a bad deal. And so if, in fact, there's no agreement, the sanctions are gonna go back in place," Boehner added.
One of the many 2016 GOP presidential candidates, Carly Fiorina, also said it is time for Obama to walk away from the deal on the same show Sunday.
“I would walk away and I would tell the Iranians that until and unless they are prepared to open every nuclear facility, every uranium enrichment facility to full and unfettered inspections, that we will make it as difficult as possible for them to move money around the global financial system," the former Hewlett-Packard chief said.
"We can do that. We don’t need anyone’s permission or collaboration to do that," Fiorina added.
-NBC News contributed to this report