Former Vice President Joe Biden on Sunday marked the one-year anniversary former Republican Sen. John McCain's death, saying the United States lost a "political giant" and a "genuine American hero."

"One year ago, we lost a political giant, and a genuine American hero—my friend, my frequent opponent—John McCain. We still feel keenly his loss in our public life," the 2020 Democratic front-runner said in a statement.

"John lived by a code that sometimes seemed to be from another era, where honor, courage, character and integrity mattered," the statement continued. "But in truth, John’s code was ageless—an American code, grounded in decency and basic fairness and an intolerance for the abuse of power. A code neither selfish, nor self-serving."

McCain died Aug. 25, 2018, just four days before he would have turned 82, after battling an aggressive brain cancer for more than a year.

Biden recalled a message from McCain's final letter to the American people, which encouraged citizens everywhere to "believe always in the promise and greatness of America, because nothing is inevitable here."

The former vice president advocated in the statement for U.S. citizens to "engage in acts of civility" in remembrance of McCain.

The statement echoed the words of Cindy McCain, the late senator's widow, who urged all Americans on CNN's State of the Union to speak with other citizens they may not see eye-to-eye with on different issues, even if it just meant agreeing to disagree.

"We've all witnessed some troubling times with regards to genuine civility towards each other and towards mankind, and our family together, all of us, felt this was a very important message that if we can convey anything that John McCain stood for on this one-year anniversary it would be acts of civility," she said.

Biden and McCain shared their differences while serving together in the Senate, though the former vice president was invited to give a eulogy at McCain's funeral.

He began his eulogy by saying, "My name is Joe Biden. I’m a Democrat. And I loved John McCain.”

Biden has faced criticism from progressives within the Democratic Party for saying he would cooperate with Republicans if elected president.

"There’s an awful lot of really good Republicans out there," he said at a Massachusetts fundraiser. "I get in trouble for saying that with Democrats, but the truth of the matter is, every time we ever got in trouble with our administration, remember who got sent up to Capitol Hill to fix it? Me. Because they know I respect the other team."