US President-elect Joe Biden delivers remarks on the Electoral College vote at the Queen Theatre in Wilmington, Delaware on Dec 14, 2020. (ROBERTO SCHMIDT / AFP)

WASHINGTON - The US Electoral College cast votes on Monday for a new president based on the 2020 election results, making Democrat Joe Biden's White House victory official.

And moments after Biden officially surpassed the 270 electoral votes needed to clinch the White House, US President Donald Trump tweeted that Attorney General William Barr will step down before Christmas.

Joe Biden, a former US vice president, surpassed 270 electoral votes after California, which has 55 Electoral College votes, the most of any state, put Biden over the top on Monday evening

Biden, a former US vice president, surpassed 270 electoral votes after California, which has 55 Electoral College votes, the most of any state, put Biden over the top on Monday evening.

Biden called on Americans to “turn the page” on the Trump era in a prime-time speech hours after prevailing over the Republican in the state-by-state Electoral College vote.

“The flame of democracy was lit in this nation a long time ago,” Biden said.“And we now know that nothing — not even a pandemic — or an abuse of power — can extinguish that flame."

"In this battle for the soul of America, democracy prevailed.”

Electors in key battleground states of Pennsylvania, Michigan, Wisconsin, Georgia and Arizona, where Trump had hotly contested but failed, voted with no surprises or defections.

ALSO READ: Explainer: What is the US Electoral College?

After electors cast their ballots based on the 2020 election results in their respective states on Monday, those results will be certified and sent to Congress, the National Archives and to the courts. Congress will certify the results of the Electoral College vote on Jan 6 as the next step in the presidential transition process.

Despite the Electoral College vote on Monday, Trump and his allies said they will continue their efforts to overturn the election results, arguing that Jan. 20, when the new president will be sworn in, is the only date set by the US Constitution. In Michigan, the state Capitol was closed during the electoral vote because of threats of violence and protests.

ALSO READ: Trump castigates Supreme Court, Barr as election challenges sputter

Dozens of lawsuits challenging the election results by Trump's campaign and his allies have been dismissed at the state and federal levels across the country since the November election.

After announcing Barr’s resignation, Trump said Deputy Attorney General Jeff Rosen will serve as acting attorney general while Richard Donoghue, former US Attorney for the Eastern District of New York, will take over Rosen's role as the No. 2 official at the Justice Department. Barr said in his resignation letter that he was departing on Dec 23.

"Just had a very nice meeting with Attorney General Bill Barr at the White House... As per letter, Bill will be leaving just before Christmas to spend the holidays with his family..." Trump tweeted. "Our relationship has been a very good one, he has done an outstanding job!" 

Earlier this month, Barr revealed that the Justice Department had not found evidence of widespread election fraud that would alter the results of the election, representing a public contradiction of Trump's election fraud claims.

READ MORE: Biden reaches deadline making victory nearly irreversible

Over the weekend, Trump slammed Barr over reports that the attorney general kept information about a federal investigation into Biden's son, Hunter Biden, from public view before the November election.

Barr has served as Trump's second attorney general since February 2019. 

Russian President Vladimir Putin on Tuesday congratulated Biden on his victory in the US presidential election, the Kremlin said.

“For my part, I am ready for interaction and contact with you,” the Kremlin cited Putin as saying in a statement.

The Kremlin had said it would wait for the official results of the election before commenting on its outcome, even as other nations congratulated Biden on the win in the days after the Nov 3 vote.

With inputs from Reuters