For Vinnie Walsh, 82, of Auburn, Mass., it was “the whole nine yards — the loss of decency, courtesy, compassion, democracy.” Laurae Carpenetti, 54, a physician from the Atlanta suburbs, said that Mr. Trump’s appointment of Robert F. Kennedy Jr. as his top health official was her motivating factor.

President Donald Trump on Tuesday did not rule out invoking the Insurrection Act if necessary to squash violence at the Los Angeles protests. “If there’s an insurrection, I would certainly invoke it,” Trump said.