The old maverick of the Senate, John McCain, slammed Donald Trump in a recent Washington Post op-ed.

The former presidential candidate, who has not kept his disdain for President Trump a secret in the past, stated “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.”

McCain took to reminding his colleagues in the Senate the “they are not his subordinates,” that Trump does not dictate the business of Congress, and that as members of Congress they work for the American people, not the President.

“We don’t answer to him. We answer to the American people… And we should value our identity as members of Congress more than our partisan affiliation,” McCain wrote.

This is not the first time in recent months that McCain has been a thorn in President Trumps side. In July he, along with fellow Republicans Lisa Murkowski (AK) and Susan Collins (ME), cast the deciding votes in the Obamacare repeal effort, effectively killing President Trump’s chances of overturning the law.

McCain has also been very critical on Trump’s possible connections with Russia.