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While President Trump insists on Twitter that ballots have been improperly counted and argues that President-elect Joe Biden's victory is premature, two sources told Fox News that Trump would concede and execute a peaceful transfer of power if his campaign's legal challenges fall short of changing the projected outcome.

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The Trump campaign has filed suits in several battleground states where Biden led by a razor-thin margin, including Nevada, Pennsylvania, and Georgia. It claimed instances of illegally counted votes from up after Election Day and that poll watchers were blocked from observing counting.

"The observers were not allowed into the counting rooms. I won the election, got 71,000 legal votes. Bad things happened which our observers were not allowed to see." Trump wrote in a Saturday evening tweet that has been labeled as disputed by Twitter. "Never happened before. Millions of mail-in ballots were sent to people who never asked for them!" 

"71,000,000 Legal Votes," he added. The most EVER for a sitting President!" 

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The latest tweets came moments after the commander in chief returned to the White House after golfing on Saturday. He walked past dozens of Biden supporters who gathered with signs that read “Good Riddance,” “You’re fired” and “Pack your s— and go.”

President Donald Trump arrives at the White House after golfing Nov. 7, in Washington. (AP Photo/Evan Vucci)

Earlier in the day, Trump accused Biden of "rushing to falsely pose as the winner" and issued a statement vowing the campaign will "start prosecuting our case in court to ensure election laws are fully upheld and the rightful winner is seated."

"The American people are entitled to an honest election: that means counting all legal ballots, and not counting any illegal ballots," Trump said. 

"It remains shocking that the Biden campaign refuses to agree with this basic principle and wants ballots counted even if they are fraudulent, manufactured, or cast by ineligible or deceased voters," Trump continued. "Only a party engaged in wrongdoing would unlawfully keep observers out of the count room – and then fight in court to block their access." 

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The Fox News Decision Desk called the race for Biden after results in Pennsylvania and Nevada put him above the 270 electoral vote threshold necessary to clinch victory in the Electoral College.

Biden and Vice President-elect Kamala Harris have attempted to calm the public, insisting that all votes will be counted no matter how long it takes. 

"It's time for America to unite. And to heal," Biden said in a statement after his win was declared. 

FOX Business' Lucas Manfredi contributed to this report.