The Justice Department announced plans Thursday to challenge Republican-drawn redistricting plans in Texas, launching another round in a years-long legal fight over voting rights between the Obama administration and the Lone Star State.

Rep. Pete Gallego (D-Tex.). (AP)

If anyone stands to benefit from this fight, it's Rep. Pete Gallego (D-Tex.).

He represents the 23rd Congressional District of Texas, a 59,000-square-mile behemoth encompassing about a quarter of the state. The district stretches from the tony western suburbs of San Antonio to rural villages packed with Democratic voters just east of El Paso. Former representative  Henry Bonilla (D-Tex.) liked to say that he had to cross three climates and two time zones to get from one end to the other.

The seat has switched parties five times in the past 20 years — a notable amount of political tumult that makes the district one of the few genuinely swing districts left in America. The district was competitive at every level in 2012: Mitt Romney won it by 3 points; Sen. Ted Cruz (R-Tex.) won by 6; and Gallego defeated GOP incumbent Quico Canseco by 5 points.

Close observers of Texas politics said they don't expect broad changes to be made to the state's current congressional map as a result of the lawsuit joined by DOJ and, at most, Democrats might gain one or two of the state's 36 House seats. But even marginal adjustments to Gallego's district could shore him up, they noted.

"The ideal circumstance, in terms of minorities in Texas [being] treated fairly, would be restoring District 23 to its previous [level of] Latino strength," said veteran Texas Democratic strategist Matt Angle.

After less than eight months in office, Gallego has drawn one declared Republican challenger, Will Hurd, a 36-year-old former CIA operative, who lost to Canseco in a 2012 GOP primary. Canseco is also said to be considering another run.

If the current map holds, Gallego and his GOP challenger will fight for votes in the San Antonio suburbs, the part of the 23rd district that is most in dispute. In an interview Tuesday as he traveled between communities near El Paso, Gallego explained why Democrats are fighting the contours of his district.

"I think you'll see when you look at the evidence in the litigation in the case, you'll see that the legislature deliberately looked for pockets of Latinos that had a high history of voter turnout and they drew them out of the district," he said. "In some cases, like in San Antonio, they went to [a neighboring district represented by] Lloyd Doggett [(D-Tex.)] and they looked for pockets of Latinos that had a very low incidence of turnout and they put them in the 23rd. There's e-mail traffic that indicates that was the case."

E-mails released two years ago as part of the ongoing legal challenge showed how Republicans discussed moving around pockets of voters in the San Antonio area. Several lawmakers objected to a court's decision to release the e-mails, saying that revealing the contents of the messages violated their right as members of Congress to free speech and debate.

Beyond Gallego's district, potential alterations to the current configuration could make the district of Rep. Blake Farenthold (R-Tex.) more Democratic, or even add a Dallas-area majority-minority district. But those are long -shot possibilities, according to Rice University political scientist Mark Jones.

"The court is probably best off either doing nothing, or touching [the map] up at the margins. And the place where they could most likely do that is the 23rd."

Gallego said he isn't dwelling on the court challenge.

"I don't think much of it: I love competition, so whoever the Republicans choose is whoever the Republicans choose. I'm going to do what I'm going to do regardless of who the Republican nominee is."

O'Keefe reported from El Paso.