Republican Senator John McCain expressed confidence that enough U.S. senators will vote against the Iran nuclear deal in an upcoming resolution on the controversial agreement.

“I am confident we’re gonna get to 60,” McCain on "The Hugh Hewitt Show" on Monday night.

However, McCain, who is the Chairman of the Armed Services Committee, warned that in order to then override a presidential veto of such a vote (called a resolution of disapproval), opponents of the Iran deal would have to enlist 13 Democrats to their side. A two-thirds majority, or 67 senators, will be needed to override President Obama, who has vowed to veto such a resolution.

Currently, only one Democratic senator, NY Sen. Chuck Schumer, has expressed opposition to the deal, whereas 18 have come out in support of the accord, according to The Hill.

Republicans hold a Senate majority of 54-44 over the Democratic Party. There are also two Independent senators.

In advance of the vote, both the White House and groups opposing the Iran deal waged intense lobbying efforts to sway undecided or undeclared Senators.