"I plan to vote for and a straight democratic ticket. It’s not based on 'accelerationism' or anything like that; the liberals are clearly more competent people," Spencer wrote on on Sunday.
Spencer, who backed in 2016, further said that "the MAGA/Alt-Right moment is over"
His tweet read: "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. So be patient. We'll have another day in the sun. We need to recover and return in a new form.
"Voting for Trump is arguably the more 'accelerationist' choice," Spencer said, referring to a radical white supremacist ideology called accelerationism.
Accelerationism rests on the idea that Western governments are irreparably corrupt. As a result, the best thing white supremacists can do is accelerate their demise by sowing chaos and creating political tension, according to .
He continued by giving examples of accelerationism: "Under [Trump's] watch cities are collapsing, we almost started World War III, the attacks on people like me increased 10 fold, etc. The simply more competent managers of decline."
In a follow-up Twitter post early Monday morning, Spencer shared an image of himself with the words: "I'm on team Joe."
His self-made slogan also took a jab at conservatives and other political groups and it read: "Liberals are clearly more competent."
But Spencer's endorsement was swiftly rejected by a spokesperson for the .
"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 campaign's director of rapid response, .
Spencer first rose to fame in 2016 when he ended his speech by quoting propaganda in German and shouted "Hail Trump! Hail our people! Hail victory!" as audience members responded by making the Nazi salute.
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."
What's more, on the eve of the 2017 Unite the Right rally in Charlottesville, Virginia, Spencer and others marched through the University of Virginia’s campus and shouted racist and anti-Semitic slogans.
Things escalated when street brawls erupted between white nationalists planning to attend the march and counter-protesters, resulting in one death and over a dozen injured.
But Spencer shifted his stance earlier this year after the killing of Iranian general .
Spencer feared that Trump's approved airstrike which resulted in the death of Soleimani brought the US to the brink of war with Iran.
"I deeply regret voting for and promoting Donald Trump in 2016," Spencer on January 7. "To the people of Iran, there are millions of Americans who do not want war, who do not hate you, and who respect your nation and its history."
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In June, Spencer was one of many .
YouTube policy disallows videos "alleging that a group is superior in order to justify discrimination," and six channels in total were found to break those rules.
On the same day, Twitch temporarily banned Trump's channel for breaking its hateful content policy, and Reddit shut down a forum for supporters of the president.