WASHINGTON - One of John McCain's final wishes as he struggled against a devastating brain cancer could not have been more clear: He did not want Donald Trump to attend his funeral.
The two men never pretended to like each other. It was not just their clashing personalities or vastly dissimilar backgrounds. Their differences were fundamental, their values dramatically at odds, and their disagreements public and pointed.
Mr McCain, a United States senator from Arizona for over three decades and former prisoner of war in Vietnam who ran unsuccessfully for US president in 2008, died on Saturday (Aug 25) at the age of 81.
President Trump tweeted on Sunday: "My deepest sympathies and respect go out to the family of Senator John McCain. Our hearts and prayers are with you!"
When Mr Trump announced his candidacy for the Republican presidential nomination in June 2015, suggesting that many Mexican immigrants were criminals and "rapists", Mr McCain denounced him for using language that "fired up the crazies".
Mr Trump's response: McCain was a "dummy" who had barely managed to graduate from the US Naval Academy.
Never one to give in, Mr Trump then attacked the former navy pilot over what might have seemed his least vulnerable point: the military career - including more than five years as a wounded and tortured prisoner of war in Vietnam - for which he received a slew of decorations including the Silver Star, the Legion of Merit and three Bronze Stars.
Mr Trump, who received serial deferments and did not serve in the military, said that Mr McCain was "a war hero (only) because he was captured", adding, "I like people that weren't captured."
That comment that drew widespread condemnation, including from several veterans groups.
Mr McCain's response starkly illustrated the two men's different characters: The senator sought no apology on his own behalf but said that Mr Trump did owe an apology "to the families of those who have sacrificed in conflict" and of those taken prisoner while "serving their country".
The rise of Mr Trump's populist candidacy in 2016 was widely seen as a disavowal of McCain-style Republicanism and of the more establishment approach he took during his own presidential run in 2008.
Eight years later, here was a man who openly professed his love of money, who had avoided military service because of a foot problem he later said had healed itself, a man who bragged about greasing the wheels for his New York real estate empire by donating to both Democrats and Republicans, a man who, in short, unapologetically flouted the long-established traditions of American politics and the presidency.
As Mr McCain pursued his own re-election to the Senate in 2016, he broke with his party's nominee after a video aired in which Mr Trump could be heard bragging that when he saw beautiful women he would sometimes "grab 'em by the pussy".
Mr McCain announced that he would instead vote for "some good conservative Republican who is qualified to be president".
PUTIN AND TRUMP
One day in November 2016, not long after Mr Trump's surprise victory over Democrat Hillary Clinton, the Arizona senator exploded when journalists in the Capitol continued to pummel him with questions about the incoming president: "Do not ask me about Donald Trump. I do not want to be rude to anyone, but I do not want to be asked about Donald Trump."
It was not an easy vow to carry out, given Mr Trump's undeniable talent for dominating political debate even while blowing up long-established norms and tenets of American domestic and foreign policy.
But what most scandalised the ageing senator was the new president's persistent refusal to acknowledge and confront Russian meddling in the US political process.
As time went on, Mr McCain's resistance grew more direct and his words sharper. As chairman of the Senate Armed Services Committee he opened his own inquiry into Russian interference.
And when he heard Mr Trump's accommodating words toward Russian President Vladimir Putin when the two met in Helsinki in July, he could contain himself no longer.
"Today's press conference in Helsinki was one of the most disgraceful performances by an American president in memory," he said in a blistering statement.
"The damage inflicted by President Trump's naivete, egotism, false equivalence, and sympathy for autocrats is difficult to calculate." Even as Mr McCain's health ebbed, he missed few opportunities to lash out at the president.
He was one of just three Republican senators to vote against - and thus defeat - a Trump-backed effort to repeal former president Barack Obama's signature healthcare law. That single vote earned lasting disdain from the president.
But Mr McCain did not back down. In an op-ed article in the Washington Post, he called the president "impulsive" and "often poorly informed". In a prepared speech that seemed directed at the president and his aides, Mr McCain denounced the "spurious nationalism" of people who "would rather find scapegoats than solve problems".
And when an October 2017 interview turned to the subject of service in the Vietnam War - a profoundly marking experience in Mr McCain's own life - he did not hold back.
"One aspect of the conflict, by the way, that I will never countenance is that we drafted the lowest-income level of America, and the highest-income level found a doctor that would say that they had a bone spur," he said. "That is wrong. That is wrong." The allusion to the medical deferment that saved a young Trump from serving in that war could not have been clearer.
The patent contempt the two men displayed for each other showed no sign of fading, even as Mr McCain continued to weaken.
A few weeks ago, Mr Trump could not even bring himself to say Mr McCain's name during a signing ceremony for a defence funding bill that fellow senators had named in the Arizona lawmaker's honour.