'Despite our differences on policy and politics, I respect Senator John McCain's service to our country,' Trump said.
Washington: Donald Trump on Monday bowed to pressure to honour the late John McCain, ordering the lowering of flags across the country to half-staff, as the late senator fired a parting shot at the president in a farewell message to the nation.
Trump's about-face came after he found himself mired in controversy over his rather conspicuous failure to pay tribute to McCain, who died Saturday at 81 after a year-long battle with brain cancer.
When veterans' groups launched appeals for a more fitting salute to McCain, a Navy veteran who was imprisoned for more than five years in Vietnam, the Republican leader -- who had no love lost for the Arizona senator -- blinked.
"Despite our differences on policy and politics, I respect Senator John McCain's service to our country," Trump said in a statement as he ordered the flag atop the White House and elsewhere to fly at half-staff until McCain's burial on Sunday.
The White House flag was lowered after McCain's death on Saturday -- but it was once again at the top of the flagpole on Monday morning.
Trump's initial silence about McCain underscored the isolation of the US leader and fuelled criticism that he is incapable of bringing a divided nation together even as it mourns a man widely seen as an American hero and a political icon.
In Phoenix, where a week of tributes to McCain was soon to get underway, Rick Davis, the two-time presidential candidate's former campaign manager, confirmed that Trump would not be attending the funeral.
The President himself said Vice President Mike Pence would speak at a ceremony honouring McCain at the US Capitol on Friday.
White House chief of staff John Kelly, Defence Secretary James Mattis and National Security Advisor John Bolton would represent the administration at his services, he added.
In Phoenix, Davis read a posthumous statement from McCain that did not spare Trump.
"We weaken our greatness when we confuse our patriotism with tribal rivalries that have sown resentment and hatred and violence in all the corners of the globe," McCain said.
"We weaken it when we hide behind walls, rather than tear them down, when we doubt the power of our ideals, rather than trust them to be the great force for change they have always been," he said -- -- an apparent reference to Trump's plans for a border wall.
"I lived and died a proud American. We are citizens of the world's greatest republic, a nation of ideals, not blood and soil," McCain continued.
"Do not despair of our present difficulties but believe always in the promise and greatness of America, because nothing is inevitable here," he said, adding that the country "will get through these challenging times."
'Not a war hero'
McCain, who served as a senator from Arizona for more than 30 years, clashed repeatedly with Trump even though they were both Republicans, and the president initially paid scant tribute to the senator after his death.
The Washington Post reported that White House Press Secretary Sarah Sanders, Chief of Staff Kelly and other senior staff had urged a statement be released referring to McCain as a "hero" -- but Trump opted to tweet instead.
"My deepest sympathies and respect go out to the family of Senator John McCain," Trump tweeted. "Our hearts and prayers are with you!"
That had been the extent of Trump's remarks on McCain's passing until the White House statement on Monday.
McCain's remains will lie in state at Arizona's capitol on Wednesday, before a public viewing Friday in the rotunda of the US Capitol -- an honour reserved for the likes of John F. Kennedy, Ronald Reagan and civil rights champion Rosa Parks.
The two men who defeated McCain in his White House campaigns, Republican George W. Bush in 2000 and Democrat Barack Obama in 2008, are expected to deliver eulogies at a Saturday service at the National Cathedral in Washington.
McCain will be buried Sunday at the US Naval Academy in Annapolis, Maryland, in a private funeral service.
In Washington, McCain's death has been a rare occasion for bipartisan praise for his lifetime in public service.
Tributes have poured in from every living former president, honouring the former Navy aviator for his courage, integrity and decency.
On Capitol Hill, his desk on the Senate floor was draped with a black cloth, and adorned with a bowl of white roses.
The enmity between Trump and McCain dates from the day the real estate tycoon announced his candidacy for the Republican presidential nomination with an attack on Mexican immigrants as criminals and rapists.
During the 2016 campaign, Trump said of McCain: "He's a war hero because he was captured. I like people that weren't captured."
In the years since, McCain was Trump's loudest Republican critic, especially as the president disrupted America's long-time alliances.
After Trump met in Helsinki with Russian President Vladimir Putin, McCain called it "one of the most disgraceful performances by an American president in memory."