Donald Trump’s bid to overturn the US election result has suffered yet another defeat as the president prepared to travel back to Washington DC after spending the Thanksgiving weekend golfing at Camp David.
Judges unanimously decided to throw out an order from a lower court preventing the state from certifying dozens of contests on its November 3 election ballot.
The said the underlying lawsuit was filed months after the expiration of a time limit in Pennsylvania's year-old mail-in voting law allowing for challenges to it.
Justices also remarked on the lawsuit's staggering demand that an entire election be overturned retroactively.
"They have failed to allege that even a single mail-in ballot was fraudulently cast or counted," Justice David Wecht wrote in a concurring opinion.
The state's attorney general, Democrat Josh Shapiro, called the court's decision "another win for Democracy".
President Donald Trump and his lawyer, Rudy Giuliani, have repeatedly and baselessly claimed that Democrats falsified mail-in ballots to steal the election. President-elect Joe Biden beat Mr Trump by more than 80,000 votes in Pennsylvania, a state Trump had won in 2016.
The lawsuit is the latest in a flurry of unsuccessful legal challenges brought by the Trump campaign and its Republican allies.
Responding on Twitter, Mr Trump wrote: “The number of ballots that our Campaign is challenging in the Pennsylvania case is FAR LARGER than the 81,000 vote margin. It’s not even close. Fraud and illegality ARE a big part of the case. Documents being completed. We will appeal!”
The president has spent the weekend at the Camp David retreat in Maryland with his family, playing golf on Saturday with his sons.
Members of the family including Donald Trump Jr, Eric Trump, Ivanka Trump and her husband Jared Kushner were pictured around a fire pit with Trump aide Dan Scavino.
On Saturday Georgia’s secretary of state, Brad Raffensperger, joined calls from Republican leaders for Mr Trump to concede.
Speaking to the Atlanta Journal-Constitution, Mr Raffensperger said: “When you lose an election, you should leave quietly. It's the will of the people that has been expressed.”