5% of Congress Was Born Abroad. Those Members Show What It Means to Be American.

Mr. Meadows, one of the president’s closest allies on Capitol Hill, pushed back, saying the real fight was over the president’s policies on the border, which Ms. Omar and the others vociferously oppose.

“He’s not racist,” Mr. Meadows said. “I probably talk to him more than anybody else, and he’s certainly not a racist.”

But to those lawmakers who have been bullied because of the color of their skin, like Representative Raja Krishnamoorthi, Democrat of Illinois, the president’s remarks were especially painful.

Mr. Krishnamoorthi came to the United States when he was three months old. His father moved to Buffalo to study engineering, and his family lived in public housing and on food stamps before they moved to Peoria, Ill., to start, as Mr. Krishnamoorthi put it, “the golden period in our lives.”

“People lifted you up and embraced you, and that’s America, that will always color my image of America,” he said, reflecting on his childhood. But he said racist heckles and taunts grew more prominent as he became an adult, during road rage situations in traffic and the like.

“I’m an ethnic, religious and a racial minority, and I’m an immigrant,” he said. “When the president says what he says, it hits home in a bigger way.”

Other immigrant lawmakers — at least the Democrats — said Mr. Trump is assailing the very idea of what it means to be an American, among them Representative Raul Ruiz, a doctor and California Democrat who was born in Mexico and is the first Latino to earn three graduate degrees from Harvard University.

“Being American is not defined by color of skin or eyes or hair or any accent,” he said. “Being American is defined by our ideas, by our diversity and by the land that we call home.”