Updated

The Trump campaign on Tuesday blasted Democratic Rep. Joaquin Castro, the brother and campaign chairman of 2020 presidential hopeful Julian Castro, for publicly posting a list of prominent Texas Trump donors’ names and employers -- accusing him of "targeting" private citizens and demanding he delete it.

The campaign told Fox News they reported Castro’s tweet to Twitter, arguing it violates the platform’s abusive behavior provision stating users cannot “engage in the targeted harassment of someone, or incite other people to do so.”

“How low have Dems sunk?” Trump campaign communications director Tim Murtaugh tweeted. “This is Joaquin Castro, Congressman & chair of his brother’s campaign. Naming private citizens & their employers, targeting them for their political views and exercising 1st Amendment rights.”

He added: “Should delete & apologize. Castro campaign should disavow.”

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Murtaugh's tweet blacked out the identifying information that Castro cited.

But the Texas congressman's original tweet included a list of San Antonio residents who had donated large amounts to the Trump campaign, along with the names of their employers. It is unclear who actually compiled the list.

“Sad to see so many San Antonians as 2019 maximum donors to Donald Trump," Castro tweeted, along with the Twitter handles of several owners of local businesses who apparently donated to Trump. “Their contributions are fueling a campaign of hate that labels Hispanic immigrants as ‘invaders.’”

Rep. Joaquin Castro, D-Texas, speaks during a news conference in February. (Getty)

The list -- titled “WHO’S FUNDING TRUMP?” -- had 44 names of donors and their employers.

A Trump campaign official slammed Castro for sharing the list of names, saying "in this political climate, particularly at a time when Democrats are associating rhetoric with violence, it's a pretty disgusting thing to do."

Castro did not respond to Fox News' request for comment but defended himself late Tuesday in response to criticism from House Minority Leader Kevin McCarthy, who tweeted that the Texas Democrat's post was "shameful and dangerous."

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"No one was targeted or harassed in my post. You know that," Castro said in response to McCarthy. "All that info is routinely published. You’re trying to distract from the racism that has overtaken the GOP and the fact that President Trump spends donor money on thousands of ads about Hispanics 'invading' America.

"Donald Trump has put a target on the back of millions," Castro went on. "And you’re too cowardly or agreeable to say anything about it. How about I stop mentioning Trump’s public campaign donors and he stops using their money for ads that fuel hate?"

Castro's tweet comes as 2020 Democratic presidential candidates are criticizing President Trump's rhetoric, and even branding him a racist, in the wake of last weekend's back-to-back mass shootings in El Paso, Texas, and Dayton, Ohio, that left 31 people dead. Democrats have ripped the president, called his statement from the White House on Monday weak, and even helped to pressure The New York Times to revise a front-page headline that did not sufficiently challenge Trump's call for unity.

Castro's brother, former Housing and Urban Development Secretary Julian Castro, also slammed the president, saying he has embraced "division and bigotry" and is "fanning the flames of hate" as a form of "political strategy."

Julian Castro did not immediately respond to Fox News' request for comment on his brother's tweet.

The White House hit back earlier Tuesday.

“There is a huge difference ... between running your mouth and running for president, and being the president and trying to bring together a nation,” Counselor Kellyanne Conway said on “Fox & Friends." “The president did not respond in kind. They politicized this over the weekend.”