Senator Mark Warner said that the United States "lost a hero" and that John McCain "served this country with honor, objective and courage for his entire life, regardless of the personal cost". Bush will deliver their remarks during a service at the National Cathedral.
The White House lowered flags to half-staff in honor of McCain, who died Saturday at age 81 after a battle with brain cancer.
Trump has tweeted his "deepest sympathies and respect" to McCain's family, although he added no words of praise for McCain himself.
Trump's brief Twitter statement said "hearts and prayers" are with the McCain family. McCain, and his son Jack, who now serves in the Navy. He has sought to bridge the divide between the devotees of Trump who dominate Republican primaries in the state and a broader electorate more favorably inclined to McCain's center-right politics.
His family released a statement the day before saying McCain was no longer accepting treatment for brain cancer.
But his perfunctory response to his death attracted particular ire on social media and was in stark contrast to the traditional gracious statements issued by presidents on the death of notable Americans.
McCain was a fearless and outspoken voice on policy and politics to the end, unswerving in his defense of democratic values and unflinching in his criticism of fellow Republicans. At John's best, he showed us what that means.
Trump and McCain's bad blood stems back to June 2015 when Trump announced he was running for president and called Mexican immigrants "rapists" and drug runners during a speech.
Mark Corallo, a former spokesman for Trump's legal team and a longtime Republican strategist, said of Trump's reaction to McCain's death that "at a time like this, you would expect more of an American president when you're talking about the passing of a true American hero".
The son and grandson of four-star admirals, McCain will be buried in the cemetery of the US Naval Academy in Annapolis, on a peaceful hillside overlooking the Severn River. On Sunday, an admiring tribute to McCain tweeted by Alexandria Ocasio-Cortez, a progressive Democratic candidate for a NY congressional seat, was greeted by hundreds of vitriolic replies attacking the dead senator and branding Ocasio-Cortez a sellout and a panderer for praising him.
During President Barack Obama's time in office, four sitting senators died: Ted Kennedy, D-Mass., in 2009; Robert Byrd, D-W.Va., in 2010; Daniel Inouye, D-Hawaii, in 2012; and Frank Lautenberg, D-N.J., in 2013.
Trump had feuded with McCain for years, most notably in 2016 when Trump said McCain was "not a war hero" because he was captured by North Vietnamese troops.
"I'd like, decades from now, little children to ask their parents, 'Who was John McCain?' " Schumer said.
State law requires Ducey to appoint someone from McCain's party to fill the seat.
"Senator McCain recognized the sacrifice and hardships military members and their families can experience and proudly served as their champion in Congress", Dunford said.
Arizona Republicans are skeptical Ducey would pick McCain's widow, in part because of questions about whether she would want to seek the nomination in 2020, but also because it could anger the pro-Trump voters that the governor will need to win in November.