The group that said they would be willing to condone such violence amounted to 20.5 percent of those surveyed, with the majority of that group answering that “in general” the use of force was at least “sometimes justified” — the remaining 3 percent answered that such violence was “usually” or “always” justified.

About 12 percent of survey respondents answered that they would be at least “somewhat willing” to resort to violence themselves to threaten or intimidate a person.

And nearly 12 percent of respondents also thought it was at least “sometimes justified” to use violence if it meant returning Donald J. Trump to the presidency.

“This went beyond my darkest expectation,” Dr. Garen J. Wintemute, the director of the UC Davis Violence Prevention Program and an emergency room physician, said in an interview on Wednesday.