Earlier this month, President Trump hurled ugly insults at a group of four Democratic congresswomen of color, saying they hated America and that they should “go back” to the countries they came from, despite the fact that all are United States citizens and all but one was born in the country.

In the days since, Mr. Trump has continued his war on people of color who have criticized him. He has assailed Representative Elijah E. Cummings, a prominent black congressman from Baltimore, and denounced the Rev. Al Sharpton, a civil rights leader.

About half of registered voters believe Mr. Trump is racist, according to a new national poll. And nearly all of the 2020 candidates have roundly condemned his comments as racist and divisive.