WASHINGTON — (CNN) Former Vice President Joe Biden believes he could have been elected president had he decided to run last year.

“The answer is that I had planned on running for president, and although it would’ve been a difficult primary, I think I could’ve won,” Biden said Friday during a Q&A interview at Colgate University. “I don’t know. Maybe not, but I thought I could’ve won.”

The former vice president said the deciding factor was the death of his son, Beau, who passed away after battling brain cancer in May 2015. Biden said he “lost part of his soul” when Beau died, and called him the “finest young man” he had ever known in his life.

“I don’t regret not running in the sense that it was the right decision for my boy, for me, for my family at the time,” Biden said. “But do I regret not being president? Yes.”

Biden said although he thought it would have been a difficult primary challenging Hillary Clinton, he said data showed he could have defeated President Donald Trump.

“I didn’t run because no man or woman should announce for President of the United States unless they can look the public in the eye and say, ‘I promise you I’m giving 100% of my attention and dedication to this effort,'” Biden said. “I knew I couldn’t do that.”

In an interview with CNN’s Jake Tapper in December, Biden, 74, wouldn’t rule out the prospect of running for the presidency in 2020 if he thinks issues of economic fairness aren’t being voiced. Earlier that month, however, he said he had “no intention of running.”

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