California Rep. Ted Lieu (D) blasted Donald Trump on Sunday, calling the president a “racist ass” for attacking his congressional colleagues by urging them to “go back” to the countries they came from.

Trump fired off a barrage of tweets condemning ”‘Progressive’ Democratic Congresswomen” who he wrote “originally came from countries whose governments are a complete and total catastrophe, the worst, most corrupt and inept anywhere in the world.”

Though he did not name the congresswomen, the president was likely referring to Democratic Reps. Alexandria Ocasio-Cortez of New York, Ilhan Omar of Minnesota, Rashida Tlaib of Michigan and Ayanna Pressley of Massachusetts. Ocasio-Cortez, Tlaib and Pressley were born in the United States, while Omar immigrated to America from Somalia when she was eight years old.

“Why don’t they go back and help fix the totally broken and crime infested places from which they came,” Trump continued.

While Republican leaders were mum on the president’s tweet storm, Democrats condemned Trump for his racist and xenophobic attack. Lieu, whose family immigrated to America when he was three years old, said he was outraged by Trump’s rhetoric.

“I never thought I would see the day when the president of the United States is telling immigrants to go back to where we came from,” Lieu said on MSNBC. “Donald Trump once again demonstrates that he’s a racist ass. He is dividing Americans rather than trying to unify us, and I can’t wait to see him leave the office of the president.”

The congressman, a frequent and vocal Trump critic, also reacted to the president’s attack on Twitter, calling his message “bigoted and unAmerican.”