Biden Looms, but Bernie Sanders Is Running His Own Race

At several stops, he also offered direct appeals to working-class voters, vowing to defend them against what he characterized as the whims of money-grabbing corporations.

In Ohio, he excoriated General Motors for closing its nearby Lordstown plant. “We are sick and tired,” he said, his voice filling the high school auditorium, “of you shutting down plants in this country and destroying families.” Those in the crowd raised their fists and applauded thunderously.

But even as a leading presidential candidate, Mr. Sanders is in many ways the same as he was as an underdog in 2016. He rarely smiles, even when he is being praised. He interrupts pointed questions from voters, then answers them with recognizable snippets from his stump speech. He does not linger at campaign stops.

Some people attending Mr. Sanders’s events appeared to yearn for a connection they did not get.

In Detroit, a crowd of mostly black voters packed into Sweet Potato Sensations, a bakery in the northwestern part of the city, for a brief question-and-answer session with Mr. Sanders, who had faced criticism in 2016 for failing to draw initial support from African-Americans.

“Is the baby in child care?” he asked a woman holding a young child in the front, trying to land a point.

“No,” she replied.

“All right,” he said.

In answer to a question on immigration, he seemed to miss the mark, too.

“I wanted to hear him say that Trump is using that hate to create something that is going to really infringe on peoples’ rights as Americans,” said David Sanchez, 36, who had posed the inquiry. “I heard, like, a canned answer, and that was pretty unfortunate actually.”