John McCain has made no secret of his contempt for Donald Trump. After news broke of a Trump campaign meeting with a Kremlin-connected lawyer in July, the Arizona senator predicted that "many more shoes would drop." Weeks later, he and fellow Republicans Lisa Murkowski (AK) and Susan Collins (ME) cast the deciding votes to kill the president's Obamacare replacement bill.

Now McCain has targeted Trump in a scathing new op-ed for the Washington Post, reminding his colleagues in the Senate that "they are not his subordinates."

"Congress must govern with a president who has no experience of public office, is often poorly informed and can be impulsive in his speech and conduct," he writes.

While McCain acknowledges that Trump's authority and constitutional responsibilities must be "respected," he cautions that Congress serves as a necessary check against his power.

"We don’t answer to him," he continues. "We answer to the American people… And we should value our identity as members of Congress more than our partisan affiliation."

Read his full column at the Washington Post.