President Obama will have a hard time getting congressional approval of a Iranian nuclear deal, according to Senate Majority Leader Mitch McConnell, R-Ky.

There have been numerous delays on the way to a long-term comprehensive deal to curb Tehran's nuclear program in exchange for sanctions relief.

"It's going to be a very hard sell," McConnell said on "Fox News Sunday." "I know there will be a strong pull not to go against the president on something that is so important to him. But it is a very hard sell."

The current framework agreement is not enough to stop Iran from eventually acquiring nuclear weapons, according to McConnell.

"We already know that it's going to leave Iran as a threshold nuclear state," he said. "We know that. It appears the administration's approach to this is to enter in any agreement Iran will get into."

McConnell also said that he believes removing economic sanctions on Iran in the hopes for good behavior is not a good strategy.

"We could have ratcheted up the sanctions even further because that's what brought them to the table in the first place," McConnell said. "That's why they were hurting."

Reports surfaced early Sunday that a provisional agreement is expected to be reached that day. The next deadline for negotiators from Iran, Britain, China, France, Germany, Russia and the U.S. is Monday, July 13.