A Democratic congressman from Texas derided presumptive GOP nominee Donald Trump as “a racist” and slammed the businessman for his attacks on “Mexican” U.S. District Judge Gonzalo Curiel in a scathing open letter on Monday.

“Mr. Trump, you’re a racist and you can take your border wall and shove it up your ass,” U.S. Rep. Filemon Vela (D-TX) wrote, as quoted by the Texas Tribune.

“Before you dismiss me as just another ‘Mexican,’ let me point out that my great-great-grandfather came to this country in 1857, well before your own grandfather,” he continued. “His grandchildren (my grandfather and his brothers) all served our country in World War I and World War II. His great-grandson, my father, served in the U.S. Army and, coincidentally, was one of the first ‘Mexican’ federal judges ever appointed to the federal bench.”

Vela noted that he supports some of Trump’s politics, including prioritizing care for veterans and deporting felons who are in the country illegally. But he wrote that “any modern-thinking person” would think building a wall at the U.S. border with Mexico is “frankly astounding and asinine.”