Justice Democrats — the progressive group that backed Rep. Alexandria Ocasio-Cortez when she was a long-shot candidate — have announced the first primary challenger they’re supporting in 2020 House races.

As part of an attempt to oust moderate, seven-term Texas Democrat Henry Cuellar, Justice Democrats are throwing their weight behind Jessica Cisneros, an immigration and human rights attorney.

“Our congressman claims to be a Democrat, but he’s voted with Trump nearly 70 percent of the time,” Cisneros said in her launch video. “He’s Trump’s favorite Democrat. Henry Cuellar voted to defund sanctuary cities and reproductive services for women’s health. He’s received an A rating from the NRA. And he’s accepted thousands of dollars from private prisons and the Koch brothers.”

Cisneros, on the other hand, touts progressive policies she supports including Medicare-for-all, the Green New Deal, and a $15 minimum wage. In the video, she pledges not to take corporate PAC money.

It’s no secret Justice Democrats have been eyeing Cuellar for a while; they announced he was their No. 1 target to primary back in January. And they are hoping Cisneros will be the next Ocasio-Cortez.

“She represents the voices we so desperately need in Congress right now — millennial, working-class, Latina, first-generation immigrant, and dedicating her life to giving back to her community,” said Alexandra Rojas, executive director of Justice Democrats. “Our grassroots progressive movement has an opportunity to build a more accountable Democratic Party by unseating one of the worst amid our ranks and ushering in a new generation of leaders.”

Cuellar’s campaign manager Colin Strother, for one, is skeptical Texas’s 28th Congressional District will vote for a progressive Democrat. Strother noted when Cuellar first ran for the seat in 2004 he did so as a more conservative primary challenger, running to the right of the incumbent. Strother adds Cuellar sees no reason to change tactics now.

“It’s a conservative district. We ran on an endorsement from the NRA,” Strother told Vox. “The Justice Democrats have been spinning some yarn that Congressman Cuellar has been deceptive and if his voters only knew his record ... no, the voters are very aware of his voting record.”

It’s worth noting Cuellar’s district swung for Hillary Clinton by 20 points. Now that Cisneros has entered the race, it could be a test of whether this southern border district has actually gotten more progressive and whether Justice Democrats can extend their primary wins beyond solid blue districts.

Texas is an interesting battleground to test Justice Democrats’ theory of political change

As Vox’s Matt Yglesias wrote earlier this year, there’s a distinct theory of political change behind Justice Democrats’ move to primary moderate Democrats: Even if you don’t win the challenge, you hopefully force the moderate incumbent further and further to the left.

Their theory of political change works not because it’s likely that left-wing challengers will unseat dozens of incumbent House Democrats but because a handful of successful challenges will scare a wide enough swath of similarly situated incumbents into moving left. Justice Democrats ... while obviously critical of the existing party establishment is — by definition — an organization that is committed to the Democratic Party and working with and through it as a vehicle for change ... The point, however, is not to displace the Democrats but to change them.

Part of the reason the group has set their sights on Cuellar is because he is so unapologetically centrist: He fundraised for a Texas Republican congressman being challenged by an insurgent Democrat in 2018, touts his glowing NRA rating, and is open about his ties to big energy groups in an area of the state where fracking is a big business.

The big question now is whether Cisneros, and Justice Democrats, can push Cuellar to the left, especially in Texas. They intentionally want Medicare-for-all and the Green New Deal to be topics of conversation in a part of the country that is not thought of as progressive.

Challenging a moderate Democrat in Texas is part of an effort to show “that these things would resonate not just in Boston and not just New York City, but places like the border,” said Waleed Shahid, a spokesperson for Justice Democrats.

Texas is a very red state that Democrats have been trying to turn purple for a long time; they had some success last year, but mostly by running moderate candidates in suburban districts outside some of its biggest cities.

Strother, a longtime Democratic operative in Texas, scoffs at the idea that Cuellar’s district is ripe for new progressive representation.

“You’ve got a for-profit group of a bunch of New York intellectuals that have never had the red dirt of South Texas on their boots, they probably don’t even have boots,” Strother said. “Coming in saying how this district should be represented ... that’s just not going to fly.”

The big questions now are whether Cuellar will move his positions on issues to the left in the run-up to November 2020 and if his constituents have the appetite for change the Justice Democrats are betting on.