Former vice president Joe Biden hasn't announced he's running for president in 2020.

But he hasn't announced he won't run, either.

"I haven't decided to run, but I've decided I'm not going to decide not run," Biden told Vanity Fair in a December issue story that published Wednesday. "We'll see what happens."

Biden's regrets about his 2016 presidential campaign that never was are well known at this point. He ultimately decided not to run after his oldest son, Beau, died from brain cancer in 2015.

In a separate interview with InStyle, he addressed the question of whether he'll announce a run: "Look. I learned a long time ago that, first, three and a half years is two lifetimes in presidential politics. And second, my family is healing. I'm sure other families have had this experience, but the loss of Beau was a devastating blow."

Of course, there's one person who would want to Biden to run: Beau himself.

After learning about Beau's brain tumor in 2013, Biden considered not running. But his sons wouldn't hear of it, especially Beau.

"At one point, he said it was my duty, my obligation to run, my duty," Biden wrote in his new book, Promise Me, Dad. "Duty was a word Beau Biden did not use lightly."

One thing to keep in mind: It was Beau's illness and subsequent death that kept Biden from running, and not anything else.

"No question," he told Vanity Fair. "I had planned on running, and I wasn't running against Hillary or Bernie or anybody else. Honest to God, I thought that I was the best suited for the moment to be president."