Sen. Bernie Sanders urged his supporters in an interview with AP Tuesday not to "sit on their hands" in the final months of the 2020 election, and to throw their support behind presumptive Democratic nominee Joe Biden.

What he's saying: "I believe that it’s irresponsible for anybody to say, 'Well, I disagree with Joe Biden — I disagree with Joe Biden! — and therefore I’m not going to be involved.'"

"I will do everything I can to help elect Joe," Sanders added. "We had a contentious campaign. We disagree on issues. But my job now is to not only rally my supporters, but to do everything I can to bring the party together to see that [Trump] is not elected president."

The big picture: Sanders suspended his campaign last week and endorsed Biden on Monday. But there's still a ways to go in rallying Sanders supporters around Biden's more moderate platform.

Biden has acknowledged this, announcing via livestream on Monday that he and Sanders are forming six task forces — a sign of Biden's continued outreach to the progressive wing of the party.

Biden made his first effort to appeal to Sanders' base last week, announcing new policy positions on Medicare and student debt.

Of note: Sanders also told AP that "it’s probably a very fair assumption" that he will not run for president again. But "one can’t predict the future," he added with a laugh.

Go deeper: How top Sanders surrogates feel about his endorsement of Joe Biden