In a series of fiery messages, Mr Trump appeared to finally concede defeat against his Democrat rival but has refused to go down quietly. It is now 12 days since the US election on November 3 and eight days since Mr Biden passed the threshold of 270 Electoral College votes needed to win the White House. In a furious post on social media, the 45th US President once again made unfounded claims of electoral fraud.
Mr Trump claimed there was no one to verify the postal votes for the Democrats.
He also launched a personal attack on the firm Demonion, which supplies election voting software, as well as the media.
Mr Trump wrote: “He won because the Election was Rigged.
“NO VOTE WATCHERS OR OBSERVERS allowed, vote tabulated by a Radical Left privately owned company, Dominion, with a bad reputation & bum equipment that couldn’t even qualify for Texas (which I won by a lot!), the Fake & Silent Media, & more!”
In a second message, Mr Trump claimed there were irregularities during the counting and votes were stolen.
More than 100 million Americans cast their ballots by post due to the coronavirus pandemic and Mr Trump branded the voting method a “sick joke”.
He added: “All of the mechanical ‘glitches’ that took place on Election Night were really THEM getting caught trying to steal votes.
“They succeeded plenty, however, without getting caught. Mail-in elections are a sick joke!”
However, minutes later Mr Trump appeared to retract his comments about Mr Biden winning the election in another stern post on Twitter.
He said: “He only won in the eyes of the FAKE NEWS MEDIA. I concede NOTHING! We have a long way to go. This was a RIGGED ELECTION!”
Following the election, the Republican leader launched a series of legal challenges in key swing-states – with allegations of electoral fraud thrown out by a number of courts.
Mr Biden won the election after receiving 306 Electoral College votes to Mr Trump’s 232 – he also leads the popular vote by more than five million.
The winning margin of 74 Electoral College votes was the same as what President Trump beat his former rival Hilary Clinton in 2016.
Unlike, Ms Clinton, the former Vice President was able to win the key Midwest states of Michigan, Pennsylvania, Wisconsin.
Mr Biden also won the traditional Republican states of Arizona and Georgia.
Leaders around the world, including Prime Minister Boris Johnson, have also recognised his election win.
Meanwhile, on Saturday night, thousands of Trump supporters held a rally in Washington and echoed his claims of election fraud.
The “Million MAGA March” referred to his campaign slogan of “Make America Great Again”.
Mr Trump and his entourage also passed through the crowds on its way to his golf course in Virginia, producing cheers from demonstrators as the president waved from the back seat.
He wrote on Twitter: “Hundreds of thousands of people showing their support in D.C. They will not stand for a Rigged and Corrupt Election!”
Dozens of Proud Boys, a far-right group, also marched in the streets, some wearing helmets and ballistic vests.
While members of the far-left movement, known as Antifa, staged their own counter-demonstrations.
The protests in the capital were largely peaceful, although a number of scuffles broke out late into the night, resulting in police making several arrests.