The late US presidential candidate John McCain will be buried today, following a five-day, cross-country funeral procession.

President Donald Trump did not play any part in McCain's farewell to the United States. McCain died of brain cancer on August 25 at the age of 81.

At McCain’s request, former presidents Barack Obama, a Democrat, and George W Bush, a Republican, spoke about the six-term senator at his final Washington event at the Washington National Cathedral. But Trump was told to stay away from all events.

Before the service, McCain's procession passed the Vietnam Veterans Memorial. McCain was a prisoner of war in Vietnam.

Former President Obama paid tribute to the man he defeated in the 2008 US presidential election.

He described McCain as an "extraordinary man - a warrior, a statesman, a patriot" who he said had shown extraordinary courage while in captivity in Vietnam and went on to be an exceptional senator who understood that principles were more important than politics.

Bush - who defeated McCain for the Republican nomination in 2000 - paid tribute to the senator's courage, honesty and sense of honour.

He said the senator often confronted those in power if he felt their conduct was falling short of America's ideals: "We are better than this. America is better than this."

Other speakers included ex-Senator Joe Lieberman and former Secretary of State Henry Kissinger.

McCain's daughter Meghan spoke ahead of the former presidents, saying her father's death was "the passing of American greatness", as she directed a message squarely at President Donald Trump while encouraging others to live up to her father's example.

In her tearful, impassioned tribute she said they "gather here to mourn the passing of American greatness - the real thing, not cheap rhetoric from men who will never come near the sacrifice he gave so willingly, nor the opportunistic appropriation of those who lived lives of comfort and privilege while he suffered and served."

She said to applause, "The America of John McCain has no need to be made great again because America was always great."

The Arizona senator will be buried on Sunday in a private ceremony at his alma mater, the US Naval Academy in Annapolis, Maryland.

McCain's coffin arrived at the capital on Friday morning as his family watched from the steps of the White House. It then took centre stage as invited guests gathered in the vast Rotunda to remember him.

"It is only right that today, near the end of his long journey, John lies here, in this great hall, under the mighty dome, like other American heroes before him," said Senate majority leader Mitch McConnell.

House speaker Paul Ryan called McCain "one of the bravest souls our nation has produced".

McCain, a former Navy aviator, really did "talk like a sailor", Ryan said, drawing smiles from the crowd. "But you see, with John, it wasn't feigned disagreement. The man didn't feign anything. He just relished the fight."

Vice-president Mike Pence said he did not always agree with McCain, but the late senator's support for limited government, tax reform and the military "surely left our nation more prosperous and more secure".

McCain "served his country honourably," Pence said, adding that Trump "respected his service to the country".