Jessica Estepa

USA TODAY

Joe Biden thinks that he could have won both the 2016 Democratic primary and the presidential election.

During a lecture series at Colgate University in New York, the former vice president admitted on Friday that he had planned on running.

"Although it would have been a very difficult primary, I think I could have won," he said.

He had data that pointed to him winning the general election as well, he said.

But the decision on whether to run came during a difficult time for Biden: His son, Beau, died of brain cancer in May 2015. Five months later, he announced that he wouldn't join the presidential race.

"I lost part of my soul," he said.

According to the Utica (N.Y.) Observer-Dispatch, Biden continued, "At the end of the day, I just couldn't do it. So I don't regret not running. Do I regret not being president? Yes."

Biden hasn't been shy about airing his regrets since leaving office. At the SXSW Conference earlier this month, he said he regretted that he wouldn't be "the president who presided over the end of cancer."