And over the weekend, the tensions resurfaced, as McCain supporters denounced the president’s tweets — and, in many cases, the president himself.

Mr. Weaver criticized Mr. Trump’s avoidance of service in Vietnam, where Mr. McCain was held captive as a prisoner of war, his refusal to release his own grades while criticizing Mr. McCain’s academic performance at the United States Naval Academy, and the president’s desire to terminate the Affordable Care Act.

“These are the things he wanted to attack John McCain on? Seriously?” Mr. Weaver said.

“I am waiting for Republican members of the Senate who served with the senator for years and allowed him to be the point of the spear on so many issues,” he said. “Where are they?”

Senator Lindsey Graham, Republican of South Carolina and one of Mr. McCain’s closest friends, chose to praise his friend rather than criticize the president.

“As to @SenJohnMcCain and his devotion to his country: He stepped forward to risk his life for his country, served honorably under difficult circumstances, and was one of the most consequential senators in the history of the body,” he said on Twitter. “Nothing about his service will ever be changed or diminished.”

Mike Murphy, another McCain political adviser, displayed no such reluctance to chastise the president: “McCain was a hero,” he said. “Trump is a whimpering coward. He was afraid to go to Vietnam 47 years ago and is afraid to face the legal consequences of his actions today.”

“He just has no empathy,” Mr. Murphy said. “He’s only concerned with himself.”

Mark Salter, one of Mr. McCain’s closest advisers and co-author of several books with him, was even more biting.