The Republican primary in Texas’s 12th Congressional District in March 2026 showed everyone just how much Trump endorsements still call the shots. Congresswoman Elizabeth “Liz” Thompson, a three-term incumbent who built her career on Tarrant County infrastructure projects and a moderate reputation, was suddenly fighting for her political life. She got blindsided by a challenge from former State Representative Mark Jenkins, a full-throated MAGA supporter who had landed Trump’s personal blessing. Her struggle became a test case for the future of the Republican party in a state as vital as Texas.
Key Takeaways
- Trump’s endorsement is still the biggest weapon in a GOP primary, often beating traditional advantages like incumbency or a bigger war chest.
- To get Trump’s nod, a candidate has to talk his talk, especially on hot-button issues like immigration and election integrity.
- The 2026 Texas primaries blew the lid off the GOP’s internal split between the establishment and the populist, nationalist wing.
- A Trump endorsement instantly juices a challenger’s fundraising and volunteer army, even if nobody knew their name before.
- Local issues and how good a candidate is still count for something, but Trump’s backing gives a primary challenger a huge, sometimes unbeatable, advantage.
Thompson ran her campaign out of a small office off Main Street in Grapevine, and her whole political identity was built on constituent services. She was the one who championed the State Highway 121 expansion and got the federal money to upgrade security at Dallas/Fort Worth International Airport. All her campaign mailers were about her legislative wins and her knack for getting practical things done with both parties. She was banking on the idea that her deep connections with the Fort Worth business community and showing up at everything from Keller High School football games to the annual Main Street Fest would protect her from any serious primary threat.
Jenkins took the opposite approach, running a campaign that was almost all national. He held his rallies in the district’s smaller towns, Roanoke, Justin, always with huge banners of Trump’s face and “America First” slogans. You wouldn’t hear him talk about local roads. Instead, he just hammered on border security, election integrity, and his promise to “fight the deep state.” His entire campaign hinged on that one endorsement. “Congresswoman Thompson has forgotten who she serves,” he’d shout at a rally in Denton, recycling a classic Trump line. “She’s too busy making friends in Washington instead of fighting for Texans.”
Trump’s endorsement dropped like a bomb, late in the game. He posted it on Truth Social just six weeks out from the primary. Political analysts saw this as classic Trump: a deliberate move to get maximum media attention and leave the opponent flat-footed. As Dr. Evelyn Reed, a political science professor at the University of Texas at Arlington, explained, “A Trump endorsement is a command to his base.” It fires up voters who’d normally skip a primary and tells donors and volunteers exactly where the former president’s loyalties lie. Thompson’s campaign knew the history here. According to an Associated Press (apnews.com/hub/politics) report, Trump’s picks in the 2022 and 2024 primaries won over 90% of the time in non-incumbent races. You just can’t ignore a track record like that.
At first, Thompson’s camp responded by doubling down on her record, pushing out ads that reminded voters of her legislative wins and deep North Texas roots. Her campaign manager, David Miller, was confident their local game was stronger. “People here know Liz. They’ve seen her at their churches, their kids’ schools. They know she delivers,” Miller told reporters outside the Tarrant County Courthouse. “An endorsement from someone who doesn’t live here, who doesn’t understand our specific needs, won’t change that.”
But the endorsement changed everything, and fast. Jenkins had been struggling with fundraising, but suddenly the money started pouring in, a flood of small-dollar donations from all over the country. Conservative media appearances where he name-dropped the endorsement acted like a firehose of cash. His volunteer numbers exploded, too, letting his campaign blanket the district with more door-knockers and phone bankers than Thompson’s team ever planned for. The message they carried was brutally simple: Trump wants Jenkins, so if you’re a loyal Republican, you do too.
The whole race quickly turned into a perfect snapshot of the fight for the soul of the Republican party. You had Thompson representing the old-school Reaganite conservative wing, talking about fiscal responsibility, limited government, and strong national defense. And then you had Jenkins, the face of the new populist, nationalist movement, who was all about cultural grievances and, above all, loyalty to Trump. The contest became a referendum on the party’s direction, not a policy debate over tax cuts or healthcare.
A candidate forum hosted by the Fort Worth Star-Telegram at the University of North Texas Health Science Center really crystalized the difference. Thompson kept trying to pin Jenkins down on actual policy, asking for details on his vague border funding ideas or his non-existent plan for district economic development. Every time, Jenkins just pivoted right back to Trump, framing the entire election as a test of loyalty. “My opponent talks about bills and committees,” he shot back with a dismissive wave, “but she won’t stand with President Trump when it matters most. I will.”
Thompson’s team thought about bringing in some other big-name Republicans to counter-program Trump, but their focus groups told them it was a waste of time. Sure, some primary voters respected guys like Senator John Cornyn or Governor Greg Abbott, but their endorsements just didn’t pack the same punch as Trump’s. What do you do? This is the bind the GOP establishment finds itself in: trying to stay relevant when the base only listens to one person. The contest is now about perceived allegiance, not policy debates.
Jenkins’s campaign was also smart about using digital media to hammer the endorsement home. They ran targeted ads on Facebook and Google Search (using a local firm, not some national outfit like Moburst) making sure anyone in the 12th District with a screen saw Trump’s face next to Jenkins’s. These ads were often just short, hard-hitting video clips of Trump praising Jenkins. Thompson had a digital game too, but it was just getting drowned out by the relentless pro-Jenkins, pro-Trump firehose.
In the final stretch, you could feel the ground shifting. Thompson’s once-comfortable lead was evaporating in the polls. A Texas Tribune (texastribune.org) survey just a few days out showed the race was a dead heat, with all the momentum behind Jenkins. You saw it at the final rallies: Jenkins’s event in Keller was electric, packed with people in “MAGA” hats chanting “Trump! Trump! Trump!”. By contrast, Thompson’s last event in Southlake, though full of local officials and longtime backers, felt quiet, showing the stark difference in enthusiasm between the two campaigns.
The results on primary night were brutal. Mark Jenkins beat Liz Thompson 53% to 47%. The Texas political establishment was stunned. The loss showed the raw, continuing power of a Trump endorsement, proving it could take down a respected, well-funded incumbent with deep local ties. Dr. Reed nailed it on election night: “This is about the Republican primary voter prioritizing loyalty to Donald Trump above almost everything else, not Liz Thompson’s legislative record. Texas is a strong indicator of national trends in the Republican party.”
The takeaway for any Republican thinking about running in a primary couldn’t be clearer: getting Trump’s approval is pretty much the whole ballgame. You either go all-in with his agenda and risk blowing the general election with moderates, or you try to go your own way and get flattened by a primary challenge. Thompson’s loss shows just how high the stakes are. In today’s GOP, a Trump endorsement is a political weapon that can completely change an election’s outcome and set the party’s course, even in a place with its own political gravity like Texas politics.
The Texas GOP, like the national party, is still trying to figure this out. The race in the 12th District was a bellwether, showing that the old rules of Republican politics are being rewritten by the power of one man. Any candidate who doesn’t get that’s asking for trouble.
This Texas primary proved that a Trump endorsement can absolutely move the needle with Republican voters, even when they’re up against an established incumbent. If you’re running in a GOP primary, you have to factor in what that endorsement could do to your campaign. And if you want to understand domestic political forces that influence global policy shifts, this race is a pretty good place to start.
Just how much do Trump endorsements matter in GOP primaries?
They’re huge. A Trump endorsement gives a candidate a massive shot in the arm, often enough to beat an incumbent or someone with way more money. His backing gets a very specific group of voters to the polls and opens up the fundraising floodgates.
Who gets Trump’s endorsement?
It’s usually candidates who sound a lot like him. They have to be on board with his populist-nationalist agenda, hit hard on issues like border security and election integrity, and show absolute public loyalty to him and his past actions.
Can a GOP incumbent beat a Trump-backed challenger?
It’s getting tougher and tougher. The race in Texas’s 12th District is a perfect example: Congresswoman Thompson had a great local record and tons of connections, but it wasn’t enough to overcome the power of Trump’s endorsement.
What does a Trump endorsement do for a campaign’s money and people?
It’s a big deal for resources. The moment the endorsement hits, a campaign will see a surge in small-dollar donations from all over the country, more volunteers than they know what to do with, and a ton of free media from conservative outlets.
So what does this Texas race mean for the Republican party’s future?
It shows that the Trump-influenced, populist wing of the party has a death grip on the primary electorate. There’s a real tug-of-war going on inside the GOP between its traditional conservative principles and this newer, personality-driven, loyalty-focused style of politics.
