He can, it’s just a dumb approach since sanctions by the Congress are meaningless unless the executive branch enforces the!. All he is doing is making the country weaker. Work with the President on a strategy and let the President sell the strategy.
It is a crime to try to force new issues of state on behalf of the United States.
McCain is not the Secretary of State, and he is not answering to, or operating on behalf of the president in an official capacity.
This is actually actionable, and with nuclear weapons involved, he has gone way over the bounds of what is permissible.