Rep. Alexandria Ocasio-Cortez, D-N.Y., continued wielding her national clout on Tuesday as she threw her weight behind Jessica Cisneros, a progressive candidate challenging yet another Democratic incumbent that Ocasio-Cortez described as non-responsive to constituent interests.

"The people of South Texas deserve a Democrat like Jessica who is going to fight for real people, not big corporate donors like the Koch Brothers, GEO Group, and Exxon," Ocasio-Cortez reportedly said in a jab at Rep. Henry Cuellar, D-Texas. Cuellar serves as the representative for the state's 28th congressional district and previously served as the state's Secretary of State.

Cuellar, who has spent more than a decade in Congress, has received criticism over support for anti-abortion legislation. He also received an "A" rating from the National Rifle Association and took donations KochPAC, a group representing the interests of Koch Industries.

“When [Cisneros] is elected, not only will I no longer be the youngest person in Congress — I’ll have a strong new ally in the fight for Medicare for All, getting corporate money out of politics, and fixing our broken immigration system," Ocasio-Cortez said, according to the group Justice Democrats.

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Cisneros, 26, previously served as Cuellar's intern. In a pinned tweet, she blasts her former boss as "Trump's favorite Democrat."

"I’m the proud daughter of Mexican immigrants and a human rights lawyer. I’m running to take on Trump’s favorite Democrat, @RepCuellar," she said. "It's time for South Texas to have a real Democrat who will fight for la gente, not corporate donors."

A campaign video shows Cisneros touting her immigrant heritage and questioning whether Cuellar is an authentic Democrat.

"Our congressman claims to be a Democrat but he's voted with Trump nearly 70 percent of the time," she says in the video. She also highlighted his votes to cut funding for sanctuary cities and abortion. "Henry Cuellar fights to protect Trump and the big corporations," she says before endorsing a slew of progressive policies like the "Green New Deal."

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Cuellar's office did not immediately respond to Fox News' request for comment.

Cuellar previously attacked Ocasio-Cortez and other members of the progressive "squad" after they targeted him for a primary. "They're socialists and they want to impose their vision to Texas and we certainly know that in Texas our vision is very different from ... what I call these Justice Democrats, which are really socialists. They're not really Democrats," he said in July.

Ocasio-Cortez, along with Justice Democrats' help, famously won her district's primary, unseating a long-term and powerful incumbent in the House of Representatives.

Since entering Congress, the freshman lawmaker has gained traction in progressive politics, fielding endorsement requests from major presidential candidates and seeing her "Green New Deal" mentioned in 2020 candidates' climate plans.

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Ocasio-Cortez has been especially critical of moderate Democrats like former Vice President Joe Biden and previous candidates who opposed "Medicare for all." Last week, she publicly endorsed Sen. Bernie Sanders, I-Vt., who has long represented a progressive insurgency pushing Democrats towards a version of socialism.

At the state and local level, she endorsed progressive challengers in Queens, New York, Illinois, and Massachusetts. It's unclear how much sway her endorsements will have in the last two as the first didn't give Tiffany Caban the boost she needed to win the rece for District Attorney.

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If previous endorsements are any judge, though, Ocasio-Cortez's latest decision will likely create even more division in the Democratic Party. Rep. Dan Lipinski, D-Ill., blasted Ocasio-Cortez as a harbinger of extremism when she endorsed his primary challenger for the 2020 election. The congresswoman responded by calling his statement "aggressive."

"Aggressive statements like these are so casually thrown from corporate candidates towards grassroots ones, yet they never get branded as 'divisive,' despite their rhetoric," she said.