Trump and Biden Campaign in Pennsylvania and Michigan on Race’s Final Weekend

President Trump and former Vice President Joseph R. Biden Jr. crisscrossed two key Northern battleground states on Saturday in a string of campaign stops with Election Day just three days away.

Mr. Trump had four rallies planned across Pennsylvania, beginning with one in Bucks County and ending in Montoursville, while Mr. Biden appeared in Flint, Mich., with plans to visit Detroit later.

The two states were part of the so-called “Blue Wall” — Michigan, Wisconsin and Pennsylvania — that have leaned Democratic in recent national elections but which were crucial to Mr. Trump’s victory in 2016 over Hillary Clinton.

Mr. Trump has struggled in all three states throughout the 2020 campaign, and is pressing to keep one of the three as part of his map this year, in an election cycle marked by a coronavirus pandemic and an economic recession.

In Bucks County, Mr. Trump delivered a subdued speech, speaking from the teleprompter at first, to several hundred people seated in folding chairs arrayed in a field in front of a stage and a podium.

“A great red wave is forming,” Mr. Trump said, showing little of the energy he does when he speaks in front of thousands of people at bigger rallies. “As sure as we’re here together, that red wave is forming. They see it on all sides and there’s nothing they can do about it.”

At one point, the president — who is hoping for either a clear win for himself or a close result that he can battle in court — asserted that the Pennsylvania results would not be clear on Election Day.

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“So you’re going to be watching on Nov. 3. I think it’s highly likely you’re not going to have a decision because Pennsylvania’s very big,” Mr. Trump said. “We’re going to be waiting. Nov. 3 is going to come and go, and we’re not going to know. And you’re going to have bedlam in our country.”

The president’s first speech took place in a field in front of the farmhouse where George Washington planned the crossing of the Delaware River. The small crowd sat close together, mostly unmasked. Unlike it has done at his other rallies, Mr. Trump’s campaign did not position energetic supporters in a stand behind him.

The president criticized Mr. Biden’s trade practices in a state hit hard in recent years by job losses and after the economic downturn this year caused by the coronavirus.

“For decades, they targeted your steel mills, shut down your plants and sent millions of your jobs overseas, all while lining their pockets with special interest cash,” Mr. Trump said. “No one embodies this betrayal and treachery more than Joe Biden.”

Mr. Trump’s teleprompter appeared to have problems at one point, but for the first 45 minutes of his appearance, the president tried to stick to a speech that appeared designed to present him in a more “presidential” light, avoiding some of the angry and defensive outbursts that have been central to his rallies.

But then he appeared to lose interest in the speech and began to riff about Mr. Biden’s son Hunter, about his own news media coverage and how unfair he thinks the coverage has been of his administration’s handling of the coronavirus pandemic.

He mocked Mr. Biden for wearing sunglasses and dismissed his Democratic rival as merely a puppet of liberal Democrats in Congress.

And he went on a long, improvised riff about his administration’s production of ventilators as he downplayed concerns about the coronavirus even as the country exceeded 90,000 new cases a day, with hospitalizations spiking. He insisted that “we are rounding the turn” and said that a vaccine to “end the pandemic once and for all” would be ready within weeks.

“We have done an incredible job. At some point they are going to recognize that,” Mr. Trump said after mocking Mr. Biden for focusing too much on the virus. “We’ve done an A-plus job. I give ourselves a D, or maybe an F, in terms of public relations.” Mr. Trump tried to correct an ad-lib from a speech he gave on Friday in which he baselessly accused doctors of trying to profit off coronavirus deaths. On Saturday, he said of Mr. Biden’s concerns about the pandemic, “We agree, we agree it’s serious,” but added that his rival’s “only plan is to make you a prisoner in your home, a prisoner in your own country.”

He manufactured a chain of events in which Representative Ilhan Omar, a Democrat of Minnesota and a favorite progressive target of Mr. Trump’s, would oversee national security should Mr. Biden win. And he talked up the voter turnout operation that the Republican Party has built over the past 18 months, saying it would prove decisive on Election Day.

Separately, for the second straight day, Mr. Biden traveled to the Upper Midwest, a critical region where he has multiple ambitions: to win back voters who drifted to Mr. Trump in 2016 and to turn out as many traditional Democratic voters, including Black residents, as possible.

After making stops in Iowa, Minnesota and Wisconsin on Friday, Mr. Biden devoted Saturday to Michigan, where Mr. Trump held a rally the day before. Mr. Biden enlisted a marquee surrogate to help his cause: former President Barack Obama.

In the past two weeks, Mr. Obama campaigned solo for Mr. Biden in Pennsylvania and Florida, but Saturday was the first time in the general election that he and Mr. Biden campaigned together in person. The former president has the potential to help Mr. Biden, who served two terms as his vice president, with key groups like Black voters as well as younger people who might not be naturally drawn to a septuagenarian moderate like Mr. Biden.

Mr. Obama laid into Mr. Trump over his handling of the pandemic, emphasizing a theme that has been a central message for Mr. Biden in the closing days of the campaign.

Noting Mr. Trump’s baseless claim that doctors were profiting from coronavirus deaths, Mr. Obama said, “He cannot fathom, he does not understand the notion that somebody would risk their life to save others without trying to make a buck.”

Mr. Trump is continuing to hold crowded rallies as the pandemic rages, and Mr. Obama ridiculed him for his obsession with crowd sizes, asking: “Did no one come to his birthday party when he was a kid? Was he traumatized?”

The Biden campaign is also planning to deploy Mr. Obama to South Florida and Atlanta on Monday, where he will try to help not only Mr. Biden, but also two Democratic Senate candidates, Jon Ossoff and the Rev. Raphael Warnock. The trip on Saturday was also an opportunity to lend a hand in a close Senate race, as Gary Peters, an incumbent Democrat, is trying to fend off a challenge from his Republican opponent, John James.

For its two events on Saturday, the Biden campaign focused on vote-rich southeast Michigan. Their first event was a drive-in rally in Flint, the largest city in Genesee County, where cars lined up in rows in a parking lot outside a high school. Mr. Biden and Mr. Obama were also scheduled to appear later Saturday at an event in Detroit where Stevie Wonder was scheduled to perform.

Mr. Obama won Michigan twice, and Genesee County is an example of a place where Democrats lost ground in a big way in 2016 compared with how the Obama-Biden ticket had fared. Hillary Clinton won the county, but by only nine points, a far cry from Mr. Obama’s 28-point victory four years earlier.

Many of the cars lined up at the rally in Flint displayed campaign signs, including those for Mr. Biden and Mr. Peters, as well as a Halloween-themed sign that showed a ghost and said, “Don’t boo, vote!”

Before the event, two large video screens showed the football game between Michigan and Michigan State — a reminder that even three days before the election, the candidates have competition for voters’ attention.