Clinton has said she believes Sanders' attacks in the 2016 primaries and his delay on an endorsement hurt her campaign.

BERLIN, Germany — Former U.S. Secretary of State and 2016 Democratic presidential nominee Hillary Clinton has expressed her skepticism about Bernie Sanders but says she will support the Democratic nominee regardless of who it is.

Clinton, who beat Sanders for the Democratic nomination only to lose the 2016 election to President Donald Trump, made waves with comments about Sanders in the new documentary “Hillary,” saying “nobody wants to work with him.”

Clinton has said she believes Sanders' delay in endorsing her in 2016 hurt her in the general campaign. She also said in her 2017 memoir that Sanders' attacks in the primary did "lasting damage" that helped Trump.

But at the Berlinale film festival Tuesday, Clinton said her top priority was unseating Trump.

“I will support the nominee, and it won’t surprise you to hear me say that I think that it’s imperative that we retire the incumbent," Clinton said.

Sanders is seen as the current front runner in the race for this year's nomination, having won the most votes in the first three contests.