Joe Biden on Monday was formally given the go-ahead by a federal agency to begin a transition to the White House, shortly after the battleground state of Michigan certified him as the winner there.
But at the same time, Republican President Donald Trump is continuing his legal challenges to the Nov. 3 election. He is alleging widespread voter fraud.
The U.S. General Services Administration, an independent agency, informed Biden, a Democrat, that his efforts to prepare for a transition - leading up to a Jan. 20 inauguration - could officially begin.
In a tweet, Trump wrote that GSA Administrator Emily Murphy and her team should "do what needs to be done with regard to initial protocols, and have told my team to do the same."
The move by the GSA means Biden's team will now have federal funds and an official office to conduct his transition over the next two months. It also paves the way for Biden and running mate Kamala Harris to receive regular national security briefings that Trump also gets.
A statement by the Biden transition said meetings would begin with federal officials on Washington's response to the coronavirus pandemic, along with discussions of national security issues.