Sen. John McCain (R-Ariz.) has been a vocal opponent of President Donald Trump — so much so that he is considered the president’s harshest critic in Congress. It comes as no surprise that McCain decided to fire yet another insult at the president on Sunday.

In a recent interview with Esquire, McCain stated that he disagrees with the way Trump is “conducting his presidency.” The senator took the fight to a personal level, too, by claiming that Trump lacks “principles and beliefs.”

The Attack

The senator acknowledged the president’s success as an entrepreneur, but his comments quickly turned negative. McCain asserted:

[Trump is] an individual that unfortunately is not anchored by a set of principles. I think he’s a person who takes advantage of situations… I don’t think there was any doubt about his views toward me. But I’m a loyal Republican.

These comments come just a month after McCain called for the United States to fulfill its “moral obligation” to continue global initiatives, and inferred that Trump and his administration were abandoning core American principles.

He said in an October speech:

To abandon the ideals we have advanced around the globe, to refuse the obligations of international leadership for the sake of some half-baked, spurious nationalism cooked up by people who would rather find scapegoats than solve problems, is as unpatriotic as an attachment to any other tired dogma of the past that Americans consigned to the ash heap of history.

McCain’s Flip Flop

However, despite calling himself “loyal” to the GOP, McCain hasn’t been a reliable Republican vote. In July, he sided with Democrats when he voted against the repeal of Obamacare, stunning his Republican colleagues.

But McCain’s constituents and colleagues — including Trump — have not forgotten the many promises of repeal made by the senator. President Trump tweeted a six-minute video montage featuring clips of McCain promising his efforts in the fight to repeal and replace Obamacare:

A few of the many clips of John McCain talking about Repealing & Replacing O’Care. My oh my has he changed-complete turn from years of talk! pic.twitter.com/t9cXG2Io86

— Donald J. Trump (@realDonaldTrump) September 26, 2017

After his vote killed the bill, McCain issued a statement:

The bill’s authors are my dear friends, and I think the world of them. I know they are acting consistently with their beliefs and sense of what is best for the country. So am I.

Upon hearing of McCain’s comments, Trump warned the senator: “At some point, I fight back and it won’t be pretty.”

In response, McCain fired back, “I’ve faced far greater challenges than this.”

The Aftermath

The word “principle” describes a fundamental truth that comprises the foundation of a belief system. By maintaining the agenda he expressed to voters over two years ago when he announced his campaign for president, Trump has demonstrated a solid grounding in principles. In contrast, McCain has repeatedly wavered from his promises. It seems the senator’s own “principles and beliefs” are a bit lacking.

Perhaps next time he considers launching a verbal attack, McCain should first reflect on himself.