WASHINGTON/WILMINGTON, Del. (Reuters) – President-elect Joe Biden will continue to lay the groundwork for his administration on Thursday against the backdrop of a resurgence of COVID-19 cases across the United States, while President Donald Trump refuses to accept the election’s outcome.

Biden named long-time adviser Ron Klain as his White House chief of staff on Wednesday, his first major appointment since winning the Nov. 3 presidential election.

Klain, who served as President Barack Obama’s “Ebola Czar” in 2014 during an outbreak of that virus in West Africa, is expected to take a leading role in the Biden administration’s response to the nationwide spike in COVID-19 cases.

Trump’s efforts to overturn the election’s results in key states have not kept Biden from making preparations to assume office on Jan. 20. The Democrat has spent much of the week huddling with advisers on staffing decisions.

The incumbent, meanwhile, has shown no sign that he will concede even as his unproven allegations of widespread voter fraud in key states have met with skepticism from judges and legal analysts.

Since the election was called for Biden by major news organizations on Saturday, Trump has maintained a minimal public schedule, preferring instead to air his grievances on Twitter, and has not addressed the climbing virus caseload nationwide.

The United States as a whole reported more than 1,450 COVID-19 deaths on Tuesday, the highest single-day count since mid-August, driving the total death toll above 239,000, according to a Reuters tally.

MORE LEADERS CONGRATULATE BIDEN

Biden clinched victory on Saturday after being called as winner in a series of battleground states, giving him more than the 270 electoral votes needed in the state-by-state Electoral College that determines who wins the presidency. Biden also was winning the national popular vote by more than 5 million votes with a few states still counting ballots.

More world leaders have recognized Biden’s victory, with Australia, Japan and South Korea joining the list of allies congratulating Biden in phone calls. China and Russia, meanwhile, have held off.

As Trump, the first U.S. president to lose a re-election bid since 1992, desperately tries to cling to power, his administration has resisted cooperating with transition efforts.

Democrats and other critics have accused Trump of aiming to undermine public trust in the U.S. election system and delegitimize Biden’s victory through unproven, anecdotal claims of voter fraud.

In Klain, meanwhile, Biden brings in a trusted and experienced operative who also served as Vice President Al Gore’s top aide during Bill Clinton’s administration. Klain also advised Gore’s presidential campaign during the 2000 Florida recount that ended with the Supreme Court handing George W. Bush the victory.

As Biden’s chief of staff during the 2008-2009 financial crisis, Klain helped oversee the implementation of the $787 billion Recovery Act that boosted the then-cratering economy.

“(Klain’s) deep, varied experience and capacity to work with people all across the political spectrum is precisely what I need in a White House chief of staff,” Biden said in a statement.

TRUMP 2024?

While Trump has remained publicly defiant over the election results, he has also been pondering another run for the presidency in 2024.

On Wednesday, he endorsed a top ally, Ronna McDaniel, to remain in her job as the chair of the Republican National Committee – an unusual move for an outgoing president.

In the meantime, Trump’s 2020 campaign continued to fight a rearguard action, bringing a new lawsuit in Michigan. The suit appeared unlikely to alter the outcome in the state, won by Trump won in 2016: he was losing by roughly 148,000 votes, or 2.6 percentage points, in unofficial Michigan vote totals, according to Edison Research.

The lawsuit made allegations of voting misconduct, with the focus on the Democratic stronghold of Wayne County, which includes Detroit. Jake Rollow, a spokesman for the Michigan Department of State, said the Trump campaign was promoting false claims to erode public confidence in the election.

“It does not change the truth: Michigan’s elections were conducted fairly, securely, transparently, and the results are an accurate reflection of the will of the people,” Rollow said in a statement.

Judges have tossed out several Trump lawsuits, and legal experts say the litigation has scant chance of changing the outcome.

One Republican strategist with ties to the White House said the legal maneuvers and push for recounts were aimed at coming up with support for Trump’s claims of voter fraud. He declined to be identified to discuss internal White House deliberations.

The strategist, like many others close to the effort, acknowledged the Trump campaign faced an uphill struggle.

“They’re looking at throwing up a hundred Hail Marys,” he said, using a football term referring to a long, desperate pass at the end of a game by a losing team with only a slim chance of success.