Texas Congressman to Trump: "Take Your Border Wall and Shove It Up Your Ass"

^{Editor's note: This story has been updated.}

WASHINGTON — U.S. Rep. Filemon Vela took a poison pen to the Republican presumptive presidential nominee, Donald Trump, in an open letter Monday morning.

"Mr. Trump, you’re a racist and you can take your border wall and shove it up your ass," the Brownsville Democrat wrote in a lengthy missive to the real estate magnate.

Later Monday, Vela elaborated on his remarks in an MSNBC interview. 

"Well, I would have liked to have spoken in a much more diplomatic fashion, but I felt like I had to speak to Donald Trump in language he understands," he said. 

• Read More Join us on Feb. 13 for a conversation with U.S. Rep. Filemon Vela, D-Brownsville.

Vela notes in the letter that he agreed with Trump on some policies, like improving veterans' care, addressing Mexican drug cartels and deporting criminal felons who are in the country illegally. But he also savages Trump for his rhetoric on those of Mexican descent and his promise to build a wall on the southern U.S. border.

"While you would build more and bigger walls on the U.S.-Mexico border, I would tear the existing wall to pieces," Vela wrote. "Why any modern-thinking person would ever believe that building a wall along the border of a neighboring country, which is both our ally and one of our largest trading partners, is frankly astounding and asinine."

Vela then defended U.S. District Court Judge Gonzalo Curiel, the judge overseeing litigation related to Trump's education enterprise, Trump University. Trump has questioned Curiel's capacity for fairness based on his Mexican heritage. Curiel was born in Indiana.

Vela then pointed out that his own family lineage in the United States goes back farther than Trump's paternal grandfather.

"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 wrote. "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."

"I will not presume to speak on behalf of every American of Mexican descent, for every undocumented worker born in Mexico who is contributing to our country every day or, for that matter, every decent citizen in Mexico," he added.

Vela further said on MSNBC that Trump is likely to lose Republican Hispanics in Texas. 

"To the extent that the Republican Party has made gains amongst Latinos in the state of Texas, that's because there have been some Republican leaders in Texas that have reached out to Hispanic voters," he said. "I think that with this kind of racist rhetoric that we're hearing from Donald Trump, that many of those Latino voters who may have previously voted Republican are going to vote for the Democratic candidate in this case." 

A request for comment from the Trump campaign was not immediately returned Monday.