Sen. Bernie Sanders (I-VT) said that the announcement of Stephen Bannon as President-elect Donald Trump’s chief strategist and senior advisor “should get us very nervous.”

In an appearance on ABC’s “The View” on Monday, Sanders painted Bannon’s inclusion atop Trump’s White House staff in light of the country’s historic struggles against racism, sexism, homophobia and the genocide of Native Americans.

“Hopefully, we have made some progress in making this country a less discriminatory society. I will be damned if we are going to go backwards and start dividing this country up again,” Sanders said.

“We are bringing our people together, we are not going back,” he continued. “We’re going to tell Mr. Bannon and any other advisers, we aren’t going to be turning on each other, we are going to be standing together in the wealthiest country in the history of the world to fight for a society and a government that works for all of us.”

The announcement of Bannon’s appointment as Trump’s chief strategist—he was listed before incoming chief of staff Reince Priebus in a transition team press release, which called them an “effective leadership team”—raised flags across the political spectrum.

Jonathan Greenblatt, the CEO of the Anti-Defamation League, wrote of Bannon’s appointment that “[i]t is a sad day when a man who presided over the premier website of the alt-right—a loose-knit group of white nationalists and unabashed anti-Semites and racists—is slated to be a senior staff member in the ‘people’s house.’”

John Weaver, the senior strategist for John Katich’s campaign for the Republican presidential nomination, wrote that “the next president named a racist, anti-semite as the co-equal of the chief of staff.”