AUSTIN, Texas (AP) — Republican Rep. Monica De La Cruz of Texas won reelection Tuesday night as the GOP showed growing strength along the U.S.-Mexico border and continued chipping away at a region that has been a longtime stronghold for Democrats.

De La Cruz centered her campaign on border security to again win over the predominately Latino and working-class district that stretches from San Antonio to the Rio Grande Valley. She was on pace to win by an even larger margin than she did in 2022 in what was a rematch with Democratic challenger Michelle Vallejo.

It was one of three closely watched House races on the Texas-Mexico border. Democratic Reps. Vicente Gonzalez and Henry Cuellar, who was on the ballot for the first time since being indicted earlier this year, were narrowly reelected.

Republicans have invested heavily into South Texas since several counties made significant shifts toward former President Donald Trump in 2020. Those gains continued this year, including Trump flipping Cameron County, one of the largest counties on the Texas border.

"Tonight we are witnessing incredible results, especially with Hispanics across the state of Texas, and we are seeing tonight generational change in South Texas," Republican Sen. Ted Cruz told supporters after his victory over U.S. Rep. Colin Allred.

"Our Hispanic communities aren't just leaving the Democratic Party, they are coming home to conservative values they never left," Cruz said.

Trump was also in reach of potentially flipping Hidalgo County, which President Joe Biden had won by 17 percentage points, along with former Democratic strongholds Starr and Webb counties.

Congressman wins under indictment

Cuellar defeated political newcomer Jay Furman in an early test of the congressman's political resilience following a May indictment on bribery charges.

Cuellar has deep roots in South Texas, serving the 28th Congressional District for nearly two decades. Republicans spent millions of dollars trying to unseat him in 2022 — the most competitive race of Cuellar's career — but still lost by double-digits.

This time around, Cuellar's biggest hurdle was maintaining support in the face of criminal charges. He and his wife were indicted for accepting nearly $600,000 in bribes for accepting money from an Azerbaijan-controlled energy company and a bank in Mexico. Cuellar has said he and his wife are innocent. In 2022, Cuellar had defeated his opponent by 13 percentage points, a much wider victory than his single-digit victory this time over Furman.

De La Cruz wins rematch

De La Cruz was the first Republican to win a congressional race in South Texas. The 15th Congressional District was one of two new seats awarded to Texas following the 2020 census, driven by the state's booming Hispanic population, and was drawn by Republican mapmakers to give them an edge.

Vallejo's campaign leaned into protecting Social Security and Medicare, which are popular programs among her primarily Latino and working-class base. De La Cruz has touted her support of tougher border security policies, including those backed by Trump.

Gonzalez narrowly reelected to Rio Grande Valley seat

Democratic U.S. Rep. Vicente Gonzalez has held onto his district in a win over former U.S. Rep. Mayra Flores.

It's a letdown for Republicans who made the race a top target this year. Flores had outraised Gonzales in her attempt to return to Congress after briefly serving an abbreviated term in 2022 following a special election under a map that was more favorable to Republicans.

Gonzalez's win in the 34th District is likely to reassure Democrats of their support with mostly Latino and working class voters in the Rio Grande Valley. Republicans have stepped up efforts in recent elections to make gains in the region after long writing off their prospects along Texas' southern border.

Republican House Speaker Mike Johnson had campaigned for Flores, who was the first Mexican-born woman elected to Congress.

Shifts in South Texas

Counties along the Texas-Mexico border made significant swings in 2020 toward Trump. The rightward shift represents a changing political landscape along the U.S.-Mexico border where border security has become a key issue for voters.

President Biden won Hidalgo County, a reliably blue district, by less than half the margin that Hillary Clinton did in 2016. In rural Zapata County, Trump flipped the county altogether after Clinton won it by 33 percentage points four years prior.

The gains have led to Republicans to invest millions of dollars into what were once considered deep blue districts.