Donald Trump has launched a fresh attack on John McCain, after his widow announced her support for the president’s Democratic rival Joe Biden.
Mr Trump tweeted that he was “never a fan” of the veteran Republican senator, who died in 2018.
He also accused Mr Biden of being Mr McCain’s “lapdog,” denouncing “bad decisions on endless wars”.
Before his death in 2018, Mr McCain was one of the president’s most outspoken Republican critics.
Mr Trump, in turn, publicly questioned his heroism during the Vietnam War.
Cindy McCain announced her support for Mr Biden in a tweet on Tuesday, saying he was the only candidate “who stands up for our values as a nation.”
“Joe and I don’t always agree on the issues, and I know he and John certainly had some passionate arguments, but he is a good and honest man,” said Mrs McCain.
In response, President Trump said she “can have Sleepy Joe!” – a nickname the president has for his rival.
“I hardly know Cindy McCain,” he added, “other than having put her on a Committee at her husband’s request.”
Cindy McCain made an address at the Democratic National Convention last month, and her endorsement may prove a hindrance to President Trump, who is trailing Mr Biden in most national polls.
Mr Biden has since thanked her, saying on Twitter that he was “deeply honoured to have your support and friendship.”
Mr McCain was the Republican party’s presidential candidate in 2008, and a senator for Arizona, a key battleground state in November’s elections.
He and Mr Trump had a fractious relationship. In 2015, Mr Trump questioned his heroism for being captured during the Vietnam War.
“He’s a war hero because he was captured,” he said. “I like people that weren’t captured.”
The president has also complained that he “didn’t get a thank you” for approving Mr McCain’s state funeral.