NEW HAVEN (AP) — Former Vice President Joe Biden, still grieving the loss of his son to cancer and unsure whether he'll run for president in 2020, said Friday that America is in a battle for the nation's soul.

The Democrat spoke before more than 1,500 people at Southern Connecticut State University, hours after he was in Maryland to accept the Naval Academy Alumni Association's Distinguished Graduate Award on behalf of Republican Sen. John McCain. McCain is battling glioblastoma, the same aggressive brain cancer Biden's son, Beau, died from in 2015.

"He's a very close friend of mine, and a political opponent, and he's in tough shape and he asked me to go to Annapolis and speak for him," Biden said. "He's my friend. So of course I went."

The New Haven Register reported that Biden talked of being a young senator, the current political climate and losing family members to death during his talk, moderated by Lucy Nalpathanchil of WNPR, Connecticut Public Radio.

He said only time would tell if he runs for president in 2020. "I have to be able to stand in front of a mirror and know that if I don't run, it's not because I'm afraid of losing, it's because there's somebody better to do it and/or because I'm not in a position to be all in," he said "The jury is still out. I've done nothing to promote running."

But Biden — who has traded harsh fighting words with President Donald Trump over who would come out on top in a hypothetical fistfight — said the U.S. can't afford eight years of the current Republican administration.

"We're in a battle for the soul of this nation," he said.