By Eli Watkins, CNN

(CNN) -- Former Vice President Joe Biden said in an interview that aired Sunday that he isn't actively planning a run for president in 2020, but he also didn't rule it out.

Biden made the remarks in an interview with Oprah Winfrey as part of a publicity tour for his new book, "Promise Me, Dad: A Year of Hope, Hardship, and Purpose," adding to speculation about whether he will jump into the next presidential race.

During the largely personal interview, Winfrey asked Biden if he has considered a 2020 run.

Biden responded, "No, not yet."

"And I say that 'not yet' because I'm a great respecter of fate," Biden said, adding that he is not currently planning or organizing a bid.

The former Vice President will be 75 years old this month, making him almost four years President Donald Trump's senior; in the interview, he pointed to his age as a reason for his uncertainty.

"I'm -- thank God right now -- in awful good health," Biden said. "But I don't know what the things are going to be two years from now."

Biden flirted with a presidential bid in the last election cycle, and his forthcoming memoir chronicles the year 2015, in which his son, Beau, died of brain cancer at age 46, and he decided against running in the presidential race out of concern for his family and the need to grieve for Beau's loss.

In the interview, Biden said he made the right call, but he repeated his regret that he had not ascended to the nation's highest office.

"I have a regret that I am not president," Biden said. "But I don't regret the decision I made because it's the right decision for my family."

Biden contended that while he thought he could have secured the Democratic nomination, he also thought Hillary Clinton would be a great president.

But, he said, as Election Day approached, he thought Clinton would lose.

"I did 83 events," Biden said. "A month out, I came back and said, 'We're going to lose this election.'"

Biden said the presidential campaign was not dedicated enough to talking about the issues, citing studies showing how little policy came up and asserting that candidates have to stake out affirmative positions.

"I'll bet you can't find 10 friends who could tell you what Hillary's position was on child care," Biden said. "Not generically, specifically. How we're going to have free college education, how it's going to be paid for. All the things that matter to those people."

Biden also pinned Clinton's loss in part on "identity politics" and bemoaned her campaign's inability to follow in the footsteps of former President Barack Obama's successful presidential bids.

"I think what happened is we got to the point where it became identity politics," Biden said. "They learned the wrong lessons from Barack's brilliant campaigns."