At the U.S. Capitol on Friday, Vice President Pence remembered McCain as a champion of America's armed forces.
Maintaining those connections is always a top priority.
"This week's celebration of the life and values and patriotism of this hero, I think have taken our country above all that", he said.
The president said a vote for Mike Braun is a vote "to Make America Great Again".
But Meghan McCain made sure Trump was part of the memorial in another way, leveling pointed criticism at the president in her eulogy.
He said: "Donald Trump's administration champions policies that are destroying our planet, destabilising worldwide order, and reaching new political depths by appealing to racism, misogyny, xenophobia and hatred".
Trump, who has repeatedly criticized the department over its handling of a probe into alleged Russian interference in the 2016 election campaign, suggested its leadership was biased against Republicans and that "people are angry".
We went in our thousands to Shannon to protest against George Bush visit in 2004...lets make this @POTUS visit to Ireland an even bigger one!
The motorcade carrying McCain's flag-draped casket paused at the Vietnam Veterans Memorial on its way to the cathedral, and his widow, Cindy McCain, placed a ceremonial wreath there.
"The America of John McCain is generous and welcoming and bold", she said.
Former Sen. Joe Lieberman, I-Conn. and 2000 vice presidential candidate, and close friend, recalled McCain's love of laughter and acceptance of religious and cultural differences.
Trump's daughter Ivanka Trump and son-in-law Jared Kushner, however, were in attendance. McCain's former colleagues looked on.
"Anything other than a trilateral agreement won't win congressional approval and would lose business support", President and CEO of the US Chamber of Commerce, Thomas Donohue, said Friday in a statement.
Bush was McCain's rival in the 2000 presidential race.
At the White House, during McCain's service, the president spent the day like any other Saturday with a series of critical tweets.
It was both a celebration of McCain's life and a somber reminder of the changing times. The two had served in the Senate together since McCain's 1986 election. Johnson, who usually moves about the Capitol on a scooter wheel chair, was a prisoner of war for almost seven years in Vietnam and shared a prison cell with McCain for part of it.
McCain's last public event, before he is laid to rest on Sunday in a private ceremony at the US Naval Academy in Annapolis, Maryland, comes a day after he was accorded the rare recognition of lying in state in the US Capitol.
Trump was expected to begin speaking at 7:20 p.m.at the Ford Center.