Speaking on the NBC program Meet the Press, Biden's pick for White House chief of staff Ron Klain said, "Donald Trump's Twitter feed doesn't make Joe Biden president or not president. The American people did that."
Trump's campaign has filed lawsuits seeking to overturn the results in multiple states, though without success, and legal experts say the litigation stands little chance of altering the outcome of the election.
A number of the claims stated that there were no vote watchers or observers from the Republican Party present in several key voting locations. A Pennsylvania
judge forced the Trump campaign's lawyers to admit in court this past week, however, that Republican observers had been in the room.
Election officials of both parties have said there is no evidence of major irregularities. Democrats and other critics have accused Trump of trying to delegitimize Biden's victory and undermine public confidence in the American electoral process. Before the election, Trump had refused to commit to a peaceful transfer of power.
Trump's refusal to concede did not change the fact that Biden is the president-elect, but it has stalled the government's normal process of preparing for a new presidential administration.
The Trump administration's decision not to recognize Biden as the winner has prevented Biden and his team from gaining access to government office space and to funding normally afforded to an incoming administration to ensure a smooth transition.
The federal agency in charge of providing those resources, the General Services Administration, has yet to recognize Biden's victory.
Senator Bernie Sanders, one of the main challengers to Biden for the Democratic presidential nomination, criticized Trump's post-election conduct.
"Trump will have the distinction of doing more than any person in the history of this country in undermining American democracy. The idea that he continues to tell his supporters that the only reason he may have lost this election was because of fraud is an absolutely disgraceful, un-American thing to do," Sanders told CNN's State of the Union program.
Biden has spent days huddled with advisers as he weighs cabinet appointments, fields congratulatory calls from world leaders and maps out the policies he will pursue after being sworn in on January 20. He is expected to continue meeting with advisers in private on Sunday.
Biden has won 306 votes in the state-by-state Electoral College system that determines the presidential winner, according to Edison Research, far more than the 270 needed to secure a majority. States are in the process of certifying their election results. The Electoral College meets to vote for the new president on December 14.
John Bolton, Trump's former national security adviser turned critic, on Sunday called on Republicans to acknowledge Biden's victory. Bolton last week accused his fellow Republicans of "coddling" and "kowtowing" to Trump as the incumbent despite his defeat.
"I think it's very important for leaders of the Republican Party to explain to our voters, who are not as stupid as the Democrats think, that in fact Trump has lost the election and his claims of election fraud are baseless," Bolton said on ABC's This Week program.
"I take this as a test for the Republican Party... I don't buy the argument that Donald Trump has hypnotized Republican voters," Bolton added.
TRUMP SUPPORTERS RALLY
On Saturday, tens of thousands of flag-waving Trump supporters ventured into Washington to echo his claims of election fraud during the "Million MAGA March," referring to Trump's campaign slogan of "Make America Great Again."
Trump's motorcade passed through the crowd on its way to his golf course in Virginia, producing cheers from demonstrators as the president waved from the back seat. The march was largely peaceful, though numerous scuffles broke out between Trump supporters and counter-protesters that continued after dark.
Klain said this week that a rapid transition is necessary to ensure the government is prepared to roll out a potential coronavirus vaccine early next year.
Tackling the raging pandemic will be a paramount priority for Biden, with the United States tallying record numbers of COVID-19 cases in recent days. More than 245,000 people in the country have died of the coronavirus since the pandemic began.