Two ex-presidents from opposing parties united on Saturday in homage to late senator and American patriot John McCain, in a momentous farewell ceremony that also rebuked the politics of toxicity and division trafficked by Donald Trump.

As millions tuned in to the nationally televised memorial attended by almost all of Washington's past and present powerbrokers, Trump himself was notably absent — fleeing the capital to head to one of his golf courses in Virginia just as eulogies to McCain were being delivered.

As Republican George W Bush and Democrat Barack Obama praised McCain for making them “better” leaders and embodying the virtue of placing country over party, the stunning contrast between the unifying ceremony and an outcast Trump only highlighted the astonishing state of US politics.

Hailing his friend as “an extraordinary man,” warrior and patriot who embodied what is best in America, Obama said McCain “made us better presidents — just as he made the Senate better, just as he made the country better.”

He was echoing similar sentiments expressed minutes earlier by Bush, who defeated McCain in a “hard fought” Republican primary battle in 2000, only to see that bitter rivalry melt away into a lasting friendship.

While Bush and Obama hail from different parties, their message Saturday was clear: US politics can and should rise to a higher level with the example set by John McCain.

McCain was conservative, to be sure, “but he did understand that some principles transcend politics, and some values transcend party,” Obama said.

“Our public life, our public discourse can seem small and mean and petty, trafficking in bombast and insult,” Obama said.

“It's a politics that pretends to be brave and tough but in fact is born of fear. John called on us to be bigger than that.”

McCain's final public ceremony before his private burial on Sunday at the US Naval Academy in nearby Annapolis, Maryland highlighted the warrior politician's call for healing.

Heavyweights from both parties gathered at the venerated cathedral, including Bill and Hillary Clinton, former vice presidents Al Gore and Dick Cheney and former secretaries of state Madeline Albright, John Kerry and Henry Kissinger, who address the gathering and hailed McCain's “honour.”

The president's daughter Ivanka Trump and her husband Jared Kushner were also present, along with Defense Secretary Jim Mattis, White House Chief of Staff John Kelly and Hollywood icon Warren Beatty.

Withering rebuke

McCain, who died last Saturday at age 81, has been lionised over the past week of extraordinary and emotional memorials and tributes, including his congressional colleagues bestowing him the rare honour of lying in state in the US Capitol on Friday.

At the funeral, Meghan McCain delivered a tear-filled tribute to her father using the words of Trump's campaign slogan as a withering rebuke of the president.

“The America of John McCain has no need to be made great again because America was always great,” she said, to extended applause.

Trump's name was not mentioned during the ceremony, but Meghan McCain's references to him unmistakable.

“We 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,” she said of her father, criticising “those who lived lives of comfort and privilege while he suffered and served” .

Earlier on Saturday McCain's flag-draped casket was taken by honour guard from the US Capitol and placed in a black hearse, which stopped at the Vietnam Veterans Memorial to allow his widow Cindy McCain to lay a wreath honoring all of those who died in the conflict.

That the men who vanquished McCain in their presidential battles were asked to speak was seen as testament to his commitment to looking beyond party and signaling that Americans, regardless of political affiliation, are rowing together in the same boat.