The 44 names Texas congressman Joaquin Castro tweeted have at least two things in common: they are all constituents in his district and moreover, they all donated the maximum amount to Donald Trump’s campaign this year.

The Democrat brother of presidential hopeful Julián Castro said the people listed – including retirees, business owners and other individuals whose names are public record – were “fuelling a campaign of hate.”

He wrote: “Sad to see so many San Antonians as 2019 maximum donors to Donald Trump – the owner of ⁦@BillMillerBarBQ⁩, owner of the ⁦@HistoricPearl, realtor Phyllis Browning, etc. Their contributions are fuelling a campaign of hate that labels Hispanic immigrants as invaders.”

Mr Castro, who also serves as campaign chairman for his brother’s presidential campaign, has subsequently tried to deflect the intense criticism from Republican lawmakers and others.

They contended that Mr Castro was “targeting” the listed donors by tweeting their names to his thousands of followers; a serious accusation in the aftermath of two weekend mass shootings in El Paso, Texas, and Dayton, Ohio, that left 31 people dead and many more wounded.

El Paso mass shooting: 20 killed at Walmart store Show all 39 1 /39 El Paso mass shooting: 20 killed at Walmart store El Paso mass shooting: 20 killed at Walmart store CCTV images of the gunman identified as Patrick Crusius The 21 year old, as he entered the Cielo Vista Walmart store in El Paso. The gunman was armed with an assault rifle and opened fire on shoppers at a packed Walmart store, killing 20. KTSM 9/AFP/Getty El Paso mass shooting: 20 killed at Walmart store Law enforcement agencies respond The Texas city’s police chief said the assault on a Walmart store on Saturday, which left another 26 people wounded, was being investigated as a potential hate crime. AFP/Getty El Paso mass shooting: 20 killed at Walmart store Shoppers exit with their hands up Shoppers exit with their hands up after a mass shooting at a Walmart in El Paso, Texas, U.S. August 3, 2019. REUTERS/Jorge Salgado NO RESALES. NO ARCHIVES. STRINGER Reuters El Paso mass shooting: 20 killed at Walmart store FBI released a picture of gunman Patrick Crusius The police officially identified the 21-year-old white male from Allen, Texas, a Dallas suburb some 650 miles east of El Paso. FBI/AP El Paso mass shooting: 20 killed at Walmart store A woman reacts after the mass shooting The attack came just minutes after a far-right manifesto appeared online. If authentic, it would make it the third mass shooting this year announced in advance on the website, which often features far-right and racist content. Reuters El Paso mass shooting: 20 killed at Walmart store Law enforcement responds to the active shooter The racist four-page document, titled “The Inconvenient Truth”, calls the Walmart attack “a response to the Hispanic invasion of Texas” and expresses support for the gunman who killed 51 people at two mosques in Christchurch, New Zealand earlier this year. AFP/Getty El Paso mass shooting: 20 killed at Walmart store A shopper hiding with an old lady behind the return and exchanges counter as the shooting began. Aaron Castaneda/Reuters El Paso mass shooting: 20 killed at Walmart store Ambulances in the car park near the scene It is ranked as the eighth-deadliest mass shooting in modern US history, after a 1984 shooting in San Ysidro, California, that claimed 21 lives. AP El Paso mass shooting: 20 killed at Walmart store Kendall Long (left) comforts Kianna Long (right) who was in the freezer section of Walmart. EPA El Paso mass shooting: 20 killed at Walmart store epa07755367 Police stand at attention after a shooting at a Walmart in El Paso, Texas, USA, 03 August 2019. According to reports, at least one person was killed and at least 18 people injured and transported to local hospitals. One suspect is in custody. EPA/IVAN PIERRE AGUIRRE IVAN PIERRE AGUIRRE EPA El Paso mass shooting: 20 killed at Walmart store Shoppers exit with their hands up. Reuters El Paso mass shooting: 20 killed at Walmart store Shopping carts sit next to a curb after the shooting. EPA El Paso mass shooting: 20 killed at Walmart store El Paso Fire Medical personnel arrive at the scene. AP El Paso mass shooting: 20 killed at Walmart store Walmart employees react after. AP El Paso mass shooting: 20 killed at Walmart store A woman runs to police near the scene. AP El Paso mass shooting: 20 killed at Walmart store Several law enforcement agencies respond. AP El Paso mass shooting: 20 killed at Walmart store People arrive at MacArthur Elementary looking for family and friends as the school is being used a re-unification centre. AP El Paso mass shooting: 20 killed at Walmart store Residents Erica Rios, 36, and Alma Rios, 61, cry outside a reunification centre. AFP/Getty El Paso mass shooting: 20 killed at Walmart store People gather in Juarez, Mexico, in a vigil for the Mexican nationals who were killed. AP El Paso mass shooting: 20 killed at Walmart store A child takes part in a vigil in Ciudad Juarez AFP/Getty El Paso mass shooting: 20 killed at Walmart store Francisco Castaneda joins mourners taking part in a vigil at El Paso High School. Reuters El Paso mass shooting: 20 killed at Walmart store Presidential candidate and former congressman Beto O'Rourke, right, meets with mass shooting survivor, Rosemary, at University Medical Centre Beto O'Rourke Facebook via AP El Paso mass shooting: 20 killed at Walmart store From left, Melody Stout, Hannah Payan, Aaliyah Alba, Sherie Gramlich and Laura Barrios comfort each other during a vigil for victims of the shooting. AP El Paso mass shooting: 20 killed at Walmart store A sign is posted near the scene Getty Images El Paso mass shooting: 20 killed at Walmart store Police cars parked below the Walmart sign block a road outside while investigating. EPA El Paso mass shooting: 20 killed at Walmart store Sherie Gramlich reacts during a vigil. AP El Paso mass shooting: 20 killed at Walmart store A man places flowers at the site Reuters El Paso mass shooting: 20 killed at Walmart store People take part in a rally against hate a day after a mass shooting at the Walmart store Reuters El Paso mass shooting: 20 killed at Walmart store Lupe Lopez holds a picture of a victim during a vigil for victims AP El Paso mass shooting: 20 killed at Walmart store People take part in a rally against hate a day after a mass shooting at a Walmart store, in El Paso, Texas, U.S. August 4, 2019. REUTERS/Jose Luis Gonzalez JOSE LUIS GONZALEZ REUTERS El Paso mass shooting: 20 killed at Walmart store Elsa Mendoza Marquez, a Mexican schoolteacher who was married and the mother of two adult children, was one of the victims Getty El Paso mass shooting: 20 killed at Walmart store People with the Mexican flag and the US flag take part in a rally against hate a day Reuters El Paso mass shooting: 20 killed at Walmart store People raise their arms in the air during a vigil for victims AP El Paso mass shooting: 20 killed at Walmart store People react and embrace each other Getty El Paso mass shooting: 20 killed at Walmart store Women light candles at a make shift memorial at the site of a mass shooting EPA El Paso mass shooting: 20 killed at Walmart store Adria Gonzalez (centre) who is being hailed as a hero for leading some Walmart customers to safety, speaks to the crowd AFP/Getty El Paso mass shooting: 20 killed at Walmart store People hold up their phones AFP/Getty Images El Paso mass shooting: 20 killed at Walmart store Beto O'Rourke speaks to the crowd AFP El Paso mass shooting: 20 killed at Walmart store People react during a prayer and candle vigil organized by the city, after a shooting left 20 people dead at the Cielo Vista Mall WalMart in El Paso, Texas, on August 4, 2019. - A shooting at a Walmart store in Texas left multiple people dead. At least one suspect was taken into custody after the shooting in the border city of El Paso, triggering fear and panic among weekend shoppers as well as widespread condemnation. It was the second fatal shooting in less than a week at a Walmart store in the US and comes after a mass shooting in California last weekend. (Photo by Mark RALSTON / AFP)MARK RALSTON/AFP/Getty Images MARK RALSTON AFP/Getty

“This is grossly inappropriate, especially in the wake of recent tragic shootings,” replied Texas senator John Cornyn.

“This win-at-all-costs mentality, publicly targeting an opponent’s supporters, and encouraging retaliation is dangerous and not what Texans have a right to expect from their members of congress.”

Republican congressman Kevin McCarthy and senator Ted Cruz offered similar sentiments. The latter accused Mr Castro of “doxxing” his own constituents.

Shortly before the gunman accused in the El Paso massacre began shooting, authorities say, he posted a manifesto warning of a “Hispanic invasion of Texas”.

For Mr Castro, the operative word there is “invasion” – a word President Trump has also used repeatedly to describe immigrants who enter through the southern border.

“[Mr Trump] cannot play the blame game,” Mr Castro tweeted. “The El Paso terrorist manifesto included language that is eerily similar to the language the president has used to dehumanise and demonise Hispanic immigrants in this country. That violence just spilled over.”

Tim Murtaugh, a Trump campaign spokesman, tweeted that Mr Castro was “inviting harassment” of the private citizens listed.

“At worst, he’s encouraging violence,” Mr Murtaugh wrote. “This is a target list.”

In a separate statement to The Washington Post, Mr Murtaugh said “this naming of private citizens and their employers is reckless and irresponsible. He is endangering the safety of people he is supposed to be representing. No one should be targeted for exercising their First Amendment rights or for their political beliefs. He should delete the tweet, apologise, and his brother’s campaign should disavow it.”

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Mr Murtaugh also said he reported Mr Castro’s tweet for harassment using Twitter’s reporting feature.

In several tweets, Mr Castro said the names he posted were publicly accessible and his tweet was not a “call to action.”

He also referred to recent reports that the Trump campaign had paid for thousands of ads on Facebook that use the word “invasion" in reference to immigration.

“Donald Trump has put a target on the back of millions,” Mr Castro said in one response. “How about I stop mentioning Trump’s public campaign donors and he stops using their money for ads that fuel hate?”