PHILADELPHIA—When Michelle Smith voted for President Biden in 2020, she thought he would help people like her, a Black mother working two jobs and raising three teenage boys in North Philadelphia. Now she says she won’t vote for him again, citing higher prices, skyrocketing rent and a feeling she has been left behind.

“I really did think he was going to help people in my situation,” said Smith, 46 years old, who earns $12.50 an hour working as a home health aide and makes Instacart deliveries for extra money. “It’s like all of them talk a good game until they get elected.”