WASHINGTON - Vermont U.S. Sen. Bernie Sanders is calling on Republican President-elect Donald Trump to rescind his White House appointment of Stephen Bannon and keep his campaign promises to the middle class.

Sanders told a sold-out crowd of students at George Washington University Wednesday night that he was disappointed with the outcome of the election, but that it's the job of progressives to hold Trump to his promises to help working class Americans.

Sanders discussed his new book, "The Revolution," and challenged Trump's views on climate change.

He also called on Trump to pull back his recent appointment of Bannon, a Breitbart News executive, as a top White House strategist. The move has drawn ire from critics who say Bannon is racist, sexist and anti-Semitic.

Sanders says the appointment is "totally unacceptable."