President Biden took a jab at his presumptive Republican rival for the presidency while campaigning in Pennsylvania.

Biden made the remark while speaking at the United Steelworkers headquarters in Pittsburgh, Pennsylvania, on Wednesday.

"Under my predecessor, who’s a little busy right now, Pennsylvania lost 275,000 jobs," Biden said while boasting of his economic policies' benefit to blue collar workers.

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Biden United Steelworkers

Biden speaks during an event at the United Steelworkers Headquarters in Pittsburgh, Pennsylvania. Biden is urging a tripling of tariffs on Chinese steel and aluminum, citing "unfair competition" while seeking to win blue-collar votes in November's election.  (ANDREW CABALLERO-REYNOLDS/AFP via Getty Images)

United Steelworkers endorsed the Biden-Harris ticket last month, applauding the president's investments in "worker-centered trade policy."

"President Biden proved time and again during his first term that he stands with working families," USW International President David McCall said in the March announcement. 

He added, "His vision and leadership allowed our nation to strengthen workers’ access to collective bargaining, grow the middle class, and embark on a path to widespread prosperity."

BIDEN RETURNS TO CAMPAIGN TRAIL AS TRUMP FORCED TO REMAIN IN COURT FOR SECOND DAY OF NEW YORK HUSH MONEY TRIAL

Biden United Steelworkers

Biden joked during his address that his rival, former President Donald Trump, is "a little busy right now" as his criminal trial is underway in New York City. (ANDREW CABALLERO-REYNOLDS/AFP via Getty Images)

While Biden is on the road campaigning, Trump is currently stuck in New York City for his criminal trial surrounding alleged hush money payments to Stormy Daniels during his successful 2016 presidential campaign. 

Trump has been charged with 34 counts of falsifying business records in the first degree. It is the first ever criminal trial of a former president.

Trump has been ordered to attend the daily court proceedings of the trial. Judge Juan Merchan told Trump that if he fails to be present, a warrant will be issued for his arrest.

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Donald Trump

Former President Donald Trump leaves Trump Tower on his way to Manhattan criminal court in New York. The hush money case is the first criminal trial of a former U.S. commander-in-chief. 

"It’s a scam. It’s a political witch hunt," Trump said after court adjourned Monday. Trump pleaded not guilty to all counts last year.

Fox News Digital's Lawrence Richard contributed to this report.