John McCain has renewed his criticism of Donald Trump, saying in an interview that the President lacks firm principles who "takes advantage" of situations.

“He’s an individual that unfortunately is not anchored by a set of principles,” Mr McCain told Esquire. “I think he’s a person who takes advantage of situations.”

The long-serving Arizona Republican has been one of the most consistent conservative voices reprimanding Mr Trump, who has repeatedly feuded with Senators of his own party.

Much of Mr McCain’s criticism has been centered on the President’s foreign policy, assailing Mr Trump for praising authoritarians and pulling back from an assertive American role in international affairs.

“I don’t agree with the way he’s conducting his presidency,” Mr McCain told Esquire.

The larger problem, Mr McCain told Esquire, was that the President does not appear to be guided by an enduring set of beliefs.

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“He was successful as a builder, an entrepreneur, and all that,” Mr McCain said. “But I don’t think he has the fundamental underpinnings of principles and beliefs.”

The two have clashed repeatedly during Mr Trump’s presidency. The President has faulted Mr McCain for casting the key vote blocking an effort to repeal Barack Obama’s signature healthcare law.