Trump went after Obama during his latest campaign stop, after the two presidents have spent the last few days trading barbs -- both on Twitter and from the podium.
"Barack Hussein Obama arrived to help Sleepy Joe because Sleepy Joe is only capable of doing one of these ever three or four days," Trump said at the Waukesha rally.
Trump recounted hearing from his aides that Obama was going to rally for his former vice president.
"They said, 'Sir, I have bad news. They said, 'Barack Hussein Obama is going to campaign for Sleepy Joe,'" Trump recounted.
Trump continued to rage against his predecessor, claiming Obama refused to endorse Biden before and after he won the Democratic nomination.
"After he won, he wouldn't endorse him, you know why? Because Obama was in shock that this guy won," Trump said.
Trump's attacks on Saturday night came after Obama trolled him for "low ratings" as he ripped into his successor in a fiery speech in support of Joe Biden earlier in the day.
"His TV ratings are down," Obama said in the speech at Florida International University.
Obama also roasted Trump for his handling of the coronavirus pandemic, claiming the president "doesn't have a plan."
"You think he's hard at work coming up with a plan to get us out of this mess? Well, I don't know, because I know he's had a tough week. Everybody's been very unfair to Donald Trump this week," Obama said.
He also questioned how Donald Trump can handle COVID-19 as "new cases are breaking records" eight months into the pandemic.