He joined Senator Mitt Romney, Republican of Utah, who had criticized the president on Tuesday. “I can’t understand why the President would, once again, disparage a man as exemplary as my friend John McCain: heroic, courageous, patriotic, honorable, self-effacing, self-sacrificing, empathetic, and driven by duty to family, country, and God,” Mr. Romney wrote on Twitter.
Other Republicans, like Senator Mitch McConnell, the majority leader, were more muted in responding to Mr. Trump’s latest attacks, choosing to emphasize their support for Mr. McCain rather than confront Mr. Trump.
Those attacks began over the weekend, when the president used his Twitter feed to berate Mr. McCain for his role in giving the F.B.I. a dossier of unverified information about Mr. Trump’s connections to Russia that was compiled by a former British spy. He brought up his vote against repealing the Affordable Care Act. He claimed that Mr. McCain, a former prisoner of war, was “last in his class” at the Naval Academy, when Mr. McCain actually graduated fifth from the bottom.
On Tuesday, seated in the Oval Office next to the president of Brazil, Jair Bolsonaro, Mr. Trump told reporters that he was “never a fan” of Mr. McCain, and never would be. And on Wednesday, Mr. Trump reiterated all those reasons in a diatribe that was part of a week that has been defined for Mr. Trump by the airing of personal feuds.
He has spent days criticizing George T. Conway III, the husband of Kellyanne Conway, one his top advisers, who has been raising alarms about the president’s mental health and calling him unfit for office via his Twitter feed.
On his way to Ohio, Mr. Trump called Mr. Conway a “whack job,” capping two days of back-and-forth with the spouse of one of his most loyal and longest-serving aides.
Mark Salter, Mr. McCain’s closest political adviser and a harsh critic of the president, said the attacks were of a piece.
“The problem isn’t Trump’s disrespect to John and his family, it’s Trump,” he said. “He’s unfit for the office, and most members of Congress know he is. I hope this latest evidence of that convinces more people that he can’t be ignored.”