In a letter to the leaders of the House Ethics Committee, Republican Reps. Matt Gaetz, Jody Hice, Debbie Lesko, Jeff Duncan, Randy Weber, and Ted Budd are calling for the committee to investigate Rep. Joaquin Castro after he posted the names of several of President Trump's donors.

In the tweet, which has generated much controversy since its posting, Castro shared an image that named donors in the San Antonio area who gave the maximum amount to Trump's campaign.

The maximum donation is $2,800 each for federal primary and general election campaigns. Election law states people who donate over $200 to these campaigns are reported to the Federal Election Commission.

“By publishing a list of private citizens who donated to his political opponent, Rep. Castro sought to encourage harassment against those citizens simply on the basis of their political beliefs," the lawmakers wrote, according to The Hill. "It cannot be fairly argued that Rep. Castro had any other purpose in posting that list and telling his activist followers that those individuals were inciting hate.

"Whether he intended to provoke physical violence or merely verbal harassment, his intent was to chill the free speech and free association rights of Americans," they continued.

Castro defended the Twitter post, saying he did not publish private information.

"Like I said, my post was actually as a San Antonian, my family has been here since 1922. It was a lament," Castro told MSNBC. "It wasn’t meant as a boycott. It wasn’t meant to target these people. It was meant to draw attention to the fact we’ve got a lot of people in our community who are respected by San Antonio, who are contributing to this guy, that’s using their money to fuel hate."

He added it was not his intention for the donors to be harassed, saying, "What I would like for them to do is think twice about supporting a guy who is fueling hate in this country."

It was later revealed some of the donors who were named had also donated money to Castro in past elections.