In a wide-ranging interview with "CBS This Morning" co-host Norah O'Donnell, Joe Biden explained what factors will go into his decision on whether to run in 2020. The former vice president is currently the Democrats' top choice to run against President Trump though Biden said he thinks it's too early for that to mean very much.

"I don't think about the polling data. I think about whether or not I should run based on very private decisions relating to my family and the loss of my son and what I want to do with the rest of my life," Biden said. "But I don't think of it in terms of can I win, can I – will I lose. That's not part of the calculation."

The 75-year-old also said his age would be a "legitimate issue" if he were to run in 2020. President Trump, a fellow septuagenarian, is three years younger than him.

"I think people are going to judge it, if I were to run. I think they're gonna judge me on my vitality. Can I still run up the steps of Air Force Two? Am I still in good shape? Am I – do I have all my faculties? Am I energetic? I think it's totally legitimate people ask those questions," Biden said.

Biden, who received the 2018 Freedom Award Wednesday night for his contribution to civil rights, has been on the road campaigning for Democrats ahead of the midterm elections. He's worried that American values are "under assault."

"I think our basic American values are at stake. Decency, honor, giving hate no safe harbor, telling the truth, understanding there's something bigger than you," Biden said. "It really is under assault. It is one of those things that I think that only a minority of the American people share his view about that is so dismissive of the basic American mores…I mean, look what the world is seeing lately. They see Charlottesville and what he says. They see him embracing these dictators around the world attacking our allies. They see in a situation where he talks about he has a policy of literally ripping children from their parents at the border, for God's sake. I mean, it's not who we are."



Walking past the Lorraine Motel where Martin Luther King Jr. was assassinated in 1968, he tells O'Donnell a lot has changed since then. Still, he remains optimistic about America's future.



"I was asked by a reporter, 'Well, if he (President Trump) changed, would you be supportive?' Absolutely. Absolutely. But stop this phony populism which is about, 'I have a problem, it's because of that immigrant or that black guy.' Or stop this, this naked nationalism which, instead of making us number one, is making us last," he said.

Earlier this month, Attorney General Eric Holder, who is considering a 2020 run himself, disagreed with Michelle Obama's mantra, 'When they go low, we go high.'" Instead, Holder said, "When they go low, we kick them."

"Well, you know that's -- I respect the attorney general, but it's not my view. I don't want to get down in the mosh pit with these guys. It's not a place I want to play. He just drags you and it's part of his strategy. Part of their strategy. Drag you down and talk about, attack each other personally," Biden said. "I think the American people are desperately looking for leaders to bring them together, not split them. We cannot function in this country without arriving at a consensus."

In an interview with "CBS Evening News" in July, President Trump called Biden his "dream opponent" for 2020, adding, "Look, Joe Biden ran three times. He never got more than 1 percent and President Obama took him out of the garbage heap, and everybody was shocked that he did."

"Well, I tell you what – well, I shouldn't say anything," Biden said. "Age has given me some wisdom."