Barack Obama accused Donald Trump of failing to take the coronavirus pandemic and the presidency seriously as he campaigned alongside Joe Boden in Michigan on the final weekend of the 2020 campaign.
Mr Obama, the 44th president, and Mr Biden, his vice president who wants to be the 46th, held drive-in rallies in Flint and Detroit.
The memories of Mr Trump’s win in Michigan and the rest of the Upper Midwest are still searing in the minds of many Democrats during this closing stretch before Tuesday’s election.
That leaves Mr Biden in the position of holding a consistent lead in the national polls and an advantage in most battlegrounds, including Michigan, yet still facing anxiety it could all slip away.
As of Saturday morning, nearly 90 million voters had already cast ballots nationwide, according to a tally by The Associated Press.
Tens of millions more will vote by the time polls close on Tuesday night.
Mr Obama said he initially hoped “for the country’s sake” that Mr Trump “might take the job seriously. He never has.”
The former president, addressing voters in dozens of cars in a Flint high school car park, seized on Mr Trump’s continued focus on the size of his campaign crowds.
“Did no one come to his birthday party when he was a kid? Was he traumatised?” Mr Obama mocked. “The country’s going through a pandemic. That’s not what you’re supposed to be worrying about.”
Mr Trump, meanwhile, made an aggressive play for pivotal Pennsylvania.
His first of four scheduled stops in Pennsylvania was in a small town in Bucks County on the eastern edge of the state.
The president railed against a recent Supreme Court ruling that will allow Pennsylvania to count mail ballots received as many as three days after polls close.
He predicted “bedlam” and “many bad things” as the nation waits for a result.
R&B legend Stevie Wonder was to perform in Detroit after Mr Biden and Mr Obama speak.
Mr Biden’s campaign announced it was sending Mr Obama to Florida and Georgia on Monday.
“Joe Biden is my brother. I love Joe Biden, and he will be a great president,” Mr Obama said on Saturday.
Mr Trump is not ceding Michigan to Mr Biden.
He visited Waterford Township, near Detroit, on Friday and held a rally in the state capital, Lansing, this past week, though the surging coronavirus cases are clouding his presidency.
The worst week of the year, in terms of new infections, arrived with election day looming. More than 99,000 Americans reported new infections on Friday, a record high, according to Johns Hopkins University.
Mr Trump told Pennsylvania voters that his administration has done “an incredible job” dealing with the pandemic. He promised that the mass distribution of a vaccine was “just weeks away”.
Mr Biden has focused almost exclusively on Mr Trump’s inability to control the pandemic.
“We’re gonna beat this virus and get it under control and the first step to doing that is beating Donald Trump,” Mr Biden said after Obama spoke in Flint.
With the campaign down to the final days, Mr Trump’s closing sprint includes, in addition to the four stops in Pennsylvania, nearly a dozen events in the final 48 hours across states he carried in 2016.
Mr Biden will close out his campaign on Monday in Pennsylvania, the state where he was born and the one he has visited more than any other.
The Biden team announced that the candidate, his wife, Jill, running mate Kamala Harris, and her husband, Doug Emhoff, plan to “fan out across all four corners of the state”.