'Results are clear'
The judgement in Pennsylvania came hours after Republicans also requested a delay in certification in Michigan, another battleground, in a letter that repeated allegations of irregularities in the state which Biden won by 155,000 votes.
They asked for a delay of two weeks to allow for a full audit of results in Wayne County, the state's largest and where majority-black Detroit is located, which was won overwhelmingly by Biden.
Michigan's board of canvassers, which includes two Democrats and two Republicans, is also due to meet Monday to certify the results.
Republican Party national committee chairwoman Ronna McDaniel and the party's Michigan chair Laura Cox called on the board to "adjourn for 14 days to allow for a full audit and investigation into those anomalies and irregularities."
Michigan's Secretary of State Jocelyn Benson has said that audits cannot be conducted until after certification because officials do not have legal access to the documents needed until then.
On Saturday, she posted on Twitter that there had been "no evidence" to draw into question the result of the election.
"In a nutshell: 5.5m Michigan citizens voted," she wrote.
"The results of their votes are clear. No evidence has emerged to undermine that."
On Friday, Trump invited Michigan lawmakers to the White House as part of his bid to subvert the voters' will, but the legislators stood firm, saying they would honor the election's outcome.
Biden has so far moderated his criticism of Trump's actions, though he has spoken of "incredibly damaging messages being sent to the rest of the world about how democracy functions," adding: "It's hard to fathom how this man thinks."
Trump has rarely appeared in public since his electoral loss, but has not given up on his provocative Twitter campaign.
"The proof pouring in is undeniable," he tweeted Saturday, when he also golfed.
"Many more votes than needed. This was a LANDSLIDE!"
Twitter slapped another warning label on his tweet, along with others he posted later.