Defense Secretary James Mattis and Secretary of State Rex Tillerson have both advocated against the White House's forthcoming changes toward America's approach to Iran.
Cotton, who has advised Trump on the change of course to Iran, said Tillerson and Mattis need to step down if they cannot get on board with the plan.
"They understand they're not the president," Cotton said. "Donald Trump is the president. Their job is to advise. His job is to decide. Their job is to make sure he has the best facts, the best thinking, presented to him in an orderly fashion and ready for decision. But he decides and they move out and execute."
"At root, though, we don't have secretaries of state and secretaries of defense to make these decisions. We elect a president, who's democratically accountable to the American people. And they say, in baseball, that the longest 18 inches is the difference between the assistant coach's seat on the bench and the manager's seat," he added.