US presidential candidate and Ohio Governor John Kasich has called on Republican senators in Congress to invoke the “nuclear option” to block attempts by Democratic lawmakers to block a vote against the Iran nuclear agreement. 

Such a move would not prevent US President Barack Obama from vetoing a Senate disapproval vote, but it would provide Republican lawmakers an opportunity to prevent a filibuster by Democrats, Kasich said.

Senate Democrats have used the filibuster tactic on three occasions this month to prevent Republican efforts to reject the Iran agreement, and GOP senators have failed to gain the 60 votes needed to overcome the filibusters.

The nuclear option, also known as the constitutional option, is an extreme parliamentary procedure that allows the US Senate to override a rule or precedent, including a filibuster, by majority vote.

The procedure allows the Senate to decide any issue by majority vote (51), although the rules of the Senate state that ending a filibuster requires the approval of 60 senators.

A filibuster is a tactic that involves legislators obstructing the passage of a bill by speaking at inordinate length when the measure is debated.

“When it comes to a treaty this critical, one that I so strongly oppose, I think the Republicans in the Senate ought to say that we are not going to permit this to be blocked because of the filibuster,” Kasich said on CNN’s “State of the Union” Sunday.

“There ought to be a vote, and there ought to be extreme measures taken in the United States Senate to achieve it. It is really critical,” he added.

Kasich has been far more moderate on the Iran accord than many of his Republican presidential rivals.

During Wednesday’s US presidential election debate, he said he would not immediately repeal the agreement and would instead enforce the deal strongly.