“The Democrats have been acting like it’s OK what Trump is doing, and it’s not OK,” said Angel Leston, 38, who owns the Casa d’Paco restaurant in Newark, New Jersey’s largest city, where Mr. Booker was mayor before being elected to the Senate.

“Now,” he added, “there’s finally some fire.”

Vivian Cox Fraser, president of the Urban League of Essex County, based in Newark, said she found herself tuning in to Mr. Booker’s speech at several points on Monday and Tuesday, encouraged by his passion.

“Somehow you have to demonstrate opposition,” she said.

“The one thing I hope is, it will be the impetus for a lot more — for us to stand up,” said Ms. Cox Fraser, who expressed concern that any cuts to education funding, social services or Medicaid would hurt the families her organization serves.

Ryan Haygood, a New Jersey civil rights lawyer, said he found Mr. Booker’s willingness to put “his full self into it” inspirational. “We need voices everywhere, on every level, fighting for the foundation and soul of this country,” said Mr. Haygood, who leads the New Jersey Institute for Social Justice.

“Thank you, Cory, for your commitment to protecting the values our country was built on,” Gov. Philip D. Murphy of New Jersey wrote on social media.