A spokesperson for Democratic presidential candidate Joe Biden rejected an endorsement from alt-right figure Richard Spencer late Sunday evening, calling the white nationalist's views "absolutely repugnant."

"When Joe Biden says we are in a battle for the soul of our nation against vile forces of hate who have come crawling out from under rocks, you are the epitome of what he means. What you stand for is absolutely repugnant. Your support is 10,000% percent unwelcome here," Andrew Bates, the director of rapid response for Biden's campaign, tweeted.

Newsweek reached out to the Biden campaign for further comment, but it did not respond by the time of publication.

Spencer, 42, previously backed Trump in the 2016 election. But he tweeted an endorsement of Biden on Sunday. "I plan to vote for Biden and a straight democratic ticket. It's not based on 'accelerationism' or anything like that; the liberals are clearly more competent people," he wrote.

In a follow-up Twitter post early Monday morning, Spencer shared an image of himself with the words: "I'm on team Joe."

"The MAGA/Alt-Right moment is over. I made mistakes; Trump is an obvious disaster; but mainly the paradigm contained flaws that we now are able to perceive. And it needs to end," Spencer wrote in a series of tweets, explaining his decision. "So be patient. We'll have another day in the sun. We need to recover and return in a new form."

Spencer and his views have been widely condemned by Democrats as well as many conservatives. The Southern Poverty Law Center has referred to Spencer as "a suit-and-tie version of the white supremacists of old."

The endorsement from Spencer of Biden was reminiscent of 2016, when former Ku Klux Klan Grand Wizard David Duke endorsed Trump. The then-GOP presidential candidate told NBC News' Meet the Press in July 2016 that he wanted to rebuke Duke's endorsement "as quick as you can say it."

Prior to that, he had drawn controversy following an interview with CNN because instead of condemning Duke's endorsement, he said he was unaware of who the white supremacist was. "I don't know anything about what you're even talking about with white supremacy or white supremacists," Trump told CNN at the time.

In 2016, Spencer rose to prominence by shouting "hail Trump" and encouraging Nazi salutes of the Republican presidential nominee at a Washington, D.C., event. Spencer has openly espoused white supremacist views, arguing publicly that the U.S. belongs to white people.

"America was, until this last generation, a white country designed for ourselves and our posterity," Spencer said at the November 2016 event where he led a crowd in "hail Trump" chanting. "It is our creation, it is our inheritance, and it belongs to us," he said.

He said that whites are "a race that travels forever on an upward path," adding that "to be white is to be a creator, an explorer, a conqueror."

Richard Spencer
Richard Spencer and his supporters clash with Virginia State Police in Emancipation Park after the "Unite the Right" rally was declared an unlawful gathering August 12, 2017 in Charlottesville, Virginia. Democratic presidential nominee Joe Biden has criticized Spencer and his followers for years, and his campaign rejected Spencer's endorsement.Chip Somodevilla/Getty

Spencer was also part of the infamous violent white supremacist "Unite the Right" rally that took place in Charlottesville in 2017. During that event, far-right demonstrators openly chanted: "Jews will not replace us." In addition to Spencer, the event was attended by former Ku Klux Klan Grand Wizard David Duke and other high-profile white supremacists.

When Biden launched his presidential campaign in April 2019, he released a video condemning the rise of white supremacists under Trump's leadership. He specifically criticized the "Unite the Right" rally in the launch video.

"I wrote at the time that we're in the battle for the soul of this nation. Well, that's even more true today. We are in the battle for the soul of this nation," Biden said.