Former Vice President Biden honored Sen. John McCain John Sidney McCainAnalysis: Biden victory, Democratic sweep would bring biggest boost to economy The Memo: Trump's strengths complicate election picture Mark Kelly: Arizona Senate race winner should be sworn in 'promptly' MORE (R-Ariz.) following the announcement of McCain's death on Saturday.

McCain died after battling the same kind of brain cancer Biden's son, Beau Biden, battled until his death in 2015.

“John McCain was many things – a proud graduate of the Naval Academy, a Senate colleague, a political opponent,” Biden tweeted on Saturday night. “But, to me, more than anything, John was a friend. He will be missed dearly.”

Biden, a former Democratic senator from Delaware, has known and been close with McCain for decades.

McCain's daughter, “The View” co-host Meghan McCain, said earlier this month that she speaks with Biden “all the time.”

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"I talk to him all the time, and he checks in on me all the time," she told Glamour in an interview.

During an appearance on "The View" in December, Biden comforted Meghan McCain on air as she grieved over her father's diagnosis.

Biden said in a Saturday statement that John McCain’s life is proof that some truths — character, courage, integrity, honor — are “timeless.”

“AS a POW, John endured the worst of what human beings can do to one another,” Biden wrote. “In politics, he fell short of his greatest ambition.”

Biden faced off against McCain as Barack Obama Barack Hussein ObamaObama warns of a 'decade of unfair, partisan gerrymandering' in call to look at down-ballot races Quinnipiac polls show Trump leading Biden in Texas, deadlocked race in Ohio Poll: Trump opens up 6-point lead over Biden in Iowa MORE’s running mate during the 2008 presidential election.

“At the end of his life, he faced a cruel and relentless disease,” Biden continued. “And yet through it all he never lost sight of what he believed most: Country First. And the spirit that drove him never extinguished: we are here to commit ourselves to something bigger than ourselves.”

The giant of the Senate and Vietnam War veteran died one day after the McCain family announced that he would be discontinuing medical treatment for brain cancer.

He was diagnosed with an aggressive glioblastoma in July 2017 and because the “progress of disease and the inexorable advance of age” had rendered “their verdict.”

McCain survived years as a prisoner of war in Vietnam to become a leading actor on the political stage for decades.