Trump has tweeted to announce a “big press conference” in Philadelphia later today.
In an earlier tweet, which has since been deleted, he said the press conference would be held by lawyers.
The event is due to take place at 11:30 local time (16:30 GMT), so stay with us for more on that later.
We are expecting more results from Pennsylvania soon. That state alone is all Joe Biden needs to win the White House.
The Democrat is currently leading there by 28,833 votes.
Trump announced the press conference after writing a series of tweets making unsubstantiated allegations of illegality in the voting process in states like Pennsylvania. All four tweets were labelled as disputed and potentially misleading by Twitter.
The president and his team have launched legal challenges in several battleground states, some of which have already been dismissed.
Joe Biden on Friday said that he was going to win the U.S. presidency as his lead grew over President Donald Trump in battleground states, although television networks held off from declaring him the victor as officials continued to count votes.
"The numbers tell us ... it's a clear and convincing story: We're going to win this race," Biden said, adding that he and his running mate Kamala Harris were already meeting with experts as they prepare for the White House.
Biden's speech was originally planned as a victory celebration, but he changed his approach in the absence of an official call from television networks and other election forecasters.
Still, it amounted to a blunt challenge to Trump. The Republican incumbent kept out of view in the White House on Friday as Biden's lead grew in the four states that will decide the outcome: Pennsylvania, Georgia, Arizona and Nevada.
Leading Trump by 4.1 million votes nationwide out of a record 147 million cast, Biden said Americans had given him a mandate to tackle the coronavirus pandemic, the struggling economy, climate change and systemic racism.
"They made it clear they want the country to come together, not continue to pull apart," Biden said.
He said he hoped to address Americans again on Saturday.
Trump has remained defiant, vowing to press unfounded claims of fraud as his Republicans sought to raise $60 million to fund lawsuits challenging the results. But some in his camp described the legal effort as disorganized, and so far they have not found success in the courts.
On the fourth day of vote counting, former Vice President Biden had a 253-to-214 lead in the state-by-state Electoral College vote that determines the winner, according to Edison Research. Democrats grew increasingly frustrated that networks had not yet called a winner.
Securing Pennsylvania's 20 electoral votes would put Biden over the 270 he needs to win the presidency after a political career stretching back nearly five decades.
Biden would also win if he prevails in two of the three other key states. Like Pennsylvania, all three were still processing ballots on Friday.