In Texas, a 26-year-old liberal takes on a moderate

Jessica Cisneros is a 26-year-old immigration lawyer from South Texas, and she's running for Congress.

She's a Democrat, aiming to unseat another Democrat: U.S. Representative Henry Cuellar.

Five years ago, Cisneros worked for Cueller as an intern.

Now, she says South Texas is ready for a progressive, like her.

(SOUNDBITE) (English) CONGRESSIONAL CANDIDATE JESSICA CISNEROS SAYING:

"The myth that south Texas is conservative is just that, a myth. And it's been perpetuated by people like Henry Cuellar, who benefit from it. That's why he hasn't had a primary challenger in over a decade."

Cuellar has represented Texas's 28th Congressional district for 15 years.

But is now up against something becoming increasingly common for moderate Democrats: A challenge from the left.

This Democratic primary contest in Texas mirrors a nationwide debate within the party, establishment versus insurgent. Centrist versus progressive.

Cisneros, who calls Cueller "Trump's favorite Democrat," says he's not doing enough to push back against the Republican president.

She's the daughter of Mexican American immigrants, and says residents of the largely Hispanic district she's hoping to represent are warming up to her policies.

(SOUNDBITE) (English) CONGRESSIONAL CANDIDATE JESSICA CISNEROS SAYING:

Once you get to the nitty gritty and tell them, like, this is how this is going to affect you -- Medicare for All, you know, that means that we deserve health care as a right, that means that we don't have to be going in to Mexico to go get our medication... Those things are super important to them."

She has won presidential candidate Elizabeth Warren's endorsement, and is one of a half-dozen progressives taking on incumbent House Democrats ahead of 2020.

Backing them are Justice Democrats, a political action committee that helped fuel Representative Alexandria Ocasio Cortez's win over Congressman Joe Crowley in 2018.

But Cuellar - who's backed by Speaker Nancy Pelosi - says the rise of these insurgent Democrats could backfire for the party.

(SOUNDBITE) (English) REPRESENTATIVE HENRY CUELLAR SAYING:

"When we have the election in November, we've got to make sure Democrats come out to vote and that we win the independents. And if we lose the independents because we're far left then that election in November in 2020 is going to go a direction that we don't want."

Earlier this year, Cuellar voted with Republicans and moderate Democrats to pass a border aid package that progressives said did not sufficiently protect migrant children.

Cuellar, however, defended his record.

As for the voters, many interviewed in the 28th district said they were not familiar with Cisneros and one who did expressed his disdain for her policies.

(SOUNDBITE) (English) JOE AGUIRRE, 57, FROM LAREDO, SAYING:

"I'll be honest, sounds like another Ocasio (Cortez). You know, the socialism, I don't think... my question is who's going to pay for it."

But for Michael Guerrero - he says Cisneros could be the change Laredo needs.

(SOUNDBITE) (English) MICHAEL GUERRERO, A 21-YEAR-OLD COLLEGE STUDENT FROM LAREDO, SAYING:

"She can help make this place a little bit better than the way it is now."

The March 3rd primary matchup between Cisneros and Cuellar will be closely watched, considered a test of just how far to the left Democrats have gone.