Democrat Joe Biden's victory in the Nov. 3 presidential election was affirmed through a vote on Monday by so-called electors from each of the U.S. states, leaving Republican President Donald Trump with not much option but to wind down his attempt to overturn the results.

The electoral vote, usually an event that is little more than a formality, had gained significance as the incumbent has yet to concede, pushing ahead with largely futile legal challenges containing baseless claims of widespread voter fraud.

U.S. President-elect Joe Biden speaks about the Electoral College vote certification process at The Queen theater on Dec. 14, 2020 in Wilmington, Delaware. (Getty/Kyodo)

Criticizing Trump for launching an "unprecedented assault" on democracy and lauding the courts' findings of no cause to question or evidence in alleged irregularities, the 78-year-old president-elect declared in his home state of Delaware, "Democracy prevailed."

"The integrity of our elections remains intact. Now it's time to turn the page, as we've done throughout our history. To unite. To heal," he said, while also highlighting the importance of tackling the coronavirus outbreak and delivering an economic relief package for people struggling due to the economic fallout of the pandemic.

In the race for the White House, a winning candidate needs to secure at least 270 of the 538 Electoral College votes allocated to the 50 states and the District of Columbia. The candidate who wins the popular vote in a state captures that state's electoral votes, usually in a winner-take-all manner.

According to a tally by U.S. media, electors awarded Biden a total of 306 votes as compared to 232 for the 74-year-old Trump.

Electors are selected by the political party of a state's popular vote-winning candidate and they are expected to vote for the people's choice in their state. There were no "faithless" electors who voted against the party's nominees on Monday.

Shortly after media reported that Biden crossed the 270-electoral vote threshold, Trump tweeted that Attorney General William Barr will be leaving the post before Christmas, less than a month before Biden will be sworn in on Jan. 20.

Barr, a Trump loyalist, was seen to have upset the president by telling The Associated Press in an interview released earlier this month that the Justice Department has "not seen fraud on a scale that could have effected a different outcome in the election."

Trump is expected to continue to resist accepting his loss, but his prospects remain increasingly dim.

Before the inauguration, there are still steps that need to be taken under the Electoral College system.

Each state's electoral votes are formally counted when the House of Representatives and the Senate assemble in a joint session on Jan. 6. Vice President Mike Pence, as president of the Republican-controlled Senate, is expected to preside over the count and announce the results of the vote.

In a last-minute attempt to challenge the electoral vote returns, members of Congress can express an objection during the joint session.

An objection to a state's electoral votes must be approved by both chambers for any contested votes to be excluded. But it is unlikely such a move would pass the Congress, given that the House is currently controlled by Democrats.

U.S. President-elect Joe Biden (R) and his wife Dr. Jill Biden in Wilmington, Delaware, on Dec. 14, 2020. (Getty/Kyodo)