Mr. Trump maintained that Mr. Biden frequently is confused about his whereabouts, during a speech in which the president mispronounced Thailand as “Thighland,” catching himself a short time later.
The president spoke as his aides struggled to get a deal for new legislation to help people suffering economic pain caused by the coronavirus, something Mark Meadows, his chief of staff, and Steven Mnuchin, the Treasury secretary, have been scrambling to achieve in negotiations with Democratic leaders. Mr. Trump has not been a meaningful part of the talks, preferring to comment from the sidelines. After a fund-raiser on Thursday evening in Ohio, he will head to his private club in New Jersey and has fund-raisers scheduled this weekend.
Mr. Trump’s swing through Ohio took him to Clyde, where he toured a Whirlpool factory. The president wore a mask as he walked through the plant, giving a thumbs-up sign to photographers nearby, a notable move given his longstanding resistance to the masks until the past few weeks.
Then, standing at a lectern with the presidential seal, his face glistening with sweat, Mr. Trump delivered a winding series of remarks that were ostensibly about trade and the economy, but that took several detours into criticizing Mr. Biden and complaining about his political lot in life.
“I had such a beautiful life before I did this,” Mr. Trump said at one point.
The president’s inability to stick to his script has infuriated and exasperated his advisers, who believe he could be in a much stronger position in the campaign if only he would stop creating so much content for his critics and opponent.
During the event, Mr. Trump announced his plan to reimpose tariffs on Canadian-made aluminum. He criticized Mr. Biden and former President Barack Obama as purveyors of “broken promises and brazen sellouts and lost jobs.”
He insisted the job outlook would improve soon, despite the sharp rise in unemployment when the pandemic began and the continued elevated levels of new claims for jobless benefits — developments that have undercut his ability to claim he has delivered on his promises of four years ago to restore American manufacturing might and middle-class opportunity.