Sen. Bernie Sanders, I-Vt., late Thursday urged fellow 2016 Democratic presidential candidate Hillary Clinton to move on from an election she lost 10 months ago.

"Our job now is really not to go backwards, it is to go forwards," Sanders said on the "Late Show with Stephen Colbert." "I think it's a little bit silly to be keeping talking about 2016. We've got too many problems."

A recently released excerpt from Clinton's forthcoming book "What Happened" shows Clinton blamed Sanders, among others, for her loss to President Trump because he used innuendo that impugned her character.

Clinton also said Sanders' attacks have caused long-term damage and made it harder to unify the party.

"Actually, the case is the progressive movement today and grassroots activism is stronger than it's been in many, many years," Sanders said.