Chip Roy, a former aide to Sen. Ted Cruz (R-Tex.), is one of 18 Republicans vying for the Republican nomination in Texas’s 21st District. (Texas Tribune/Texas Tribune)

One candidate’s campaign signs declare “MAGA,” referencing President Trump’s mantra of “Make America Great Again.” Another’s is promising to “drain the swamp” and plays up his ties to a key Trump political adviser. And another’s promises to “Make America Like Texas,” a slogan spelled out in the Trump campaign’s signature font.

In several crowded Texas congressional primaries Tuesday, Republican candidates have decided that the best way to stand out is to stand squarely in Trump’s shadow — a campaign strategy that has been only slightly scrambled since the president’s sudden embrace of gun control and protectionist tariffs last week.

With some notable exceptions, candidates in one especially raucous Republican primary — the 18-person contest to fill the 21st District seat being vacated by Rep. Lamar Smith — have been wary of showing any daylight between their position and Trump’s. That has remained true even as Democratic turnout surged in early voting and national Democrats tout a chance to flip the seat, long held by a Republican.

“I think if you’re not with the president, you’re not going to have a chance of winning this race,” said Jason Isaac, a state representative who is running for the seat.

Isaac’s “Make America Like Texas” message is calibrated to couple Trump’s charisma to the more traditional Lone Star brand of small-government conservatism: “When I talk to people that move to Texas, I say, ‘Welcome to Texas, vote accordingly,’ because it’s not a mistake,” he said. “Our model works.”

Robert Stovall, a former chairman of the Bexar County Republican Party, has been even more aggressive about his support for Trump. A TV spot has Stovall standing in a swamp, wearing waders and a Trump campaign hat and pledging to help Trump “get rid of the establishment politicians who have failed to support his agenda.”

He is also touting the support of Brad Parscale, the digital guru for Trump’s 2016 campaign who was recently named to manage the president’s reelection campaign.

Stovall said in an interview that he is unique in squarely backing Trump even before he won the Republican nomination in 2016 — bucking, among others, the state’s dominant figure in national GOP politics, Sen. Ted Cruz.

Voters “want somebody that’s going to go out there and work with Donald Trump and help get his agenda moving forward,” Stovall said. “There’s been resistance even from our own party on helping him out, and they don’t want to elect somebody in this district that’s going to be a hindrance.”

Smith, who is retiring after 16 terms, has not made an endorsement in the race. “Half of them I’ve never heard of before,” he said in an interview, adding that Trump remains popular among his constituents. “They appreciate what the president has done. They appreciate the tax cut, and they appreciate the president’s efforts to enforce immigration laws.”

While the race to succeed Smith is jam-packed, other races also feature many candidates. Nine Republicans are running in the 2nd District for the Houston-area seat being vacated by Rep. Ted Poe (R). In the 5th District, eight Republicans are seeking the Dallas-area seat held by retiring Rep. Jeb Hensarling (R). And 11 are running for the adjacent 6th District seat now held by Rep. Joe Barton (R), who is stepping down after 17 terms.

Outright winners are unlikely to be chosen Tuesday in any of the GOP races, where candidates need a majority to avoid a May 22 runoff. Matt Mackowiak, a Republican consultant and chairman of the Travis County GOP, said a 21st District candidate could make the runoff with as little as 15 percent of the vote, making organization, name recognition and fundraising key factors.

Having a unique message, he said, is less of a factor: “Of the real contenders, there just hasn’t been a lot of distance from Trump on any real issues.”

Cruz’s shadow looms over the 21st District primary thanks to his aggressive backing of Chip Roy, a former top aide to Cruz and other high-profile Texas officials.

Roy, who declined a request for an interview, is the best-funded candidate in the race — thanks to a national network of conservative donors and the backing of the Club for Growth, whose super PAC has spent more than $500,000 on Roy’s behalf — much of it on ads featuring Cruz calling Roy the “real conservative” in the race.

The message, one of the few hitting TV airwaves, could be breaking through: Rich Lake, 57, cast his ballot for Roy during early voting on Thursday in the Hill Country town of Fredericksburg. Lake said the Cruz endorsement was decisive: “If Ted can work with him, then I figure there’s a good chance he can work with everybody else.”

But others voting at the Gillespie County Courthouse were overwhelmed by the long list of candidates on the ballot and skipped the congressional race. “There were so many that I didn’t recognize,” said Dennis Houy, a landscaper for the county facilities department.

Other competitive candidates in the race include Francisco “Quico” Canseco, who was elected in 2010 to represent the neighboring 23rd District for one term and has since sought to come back to Congress, and Susan Narvaiz, a former mayor of San Marcos, Tex., a rapidly growing city between San Antonio and Austin.

The influx of national money and the fact that several candidates — including Roy, Isaac and Canseco — live outside the district has sparked frustrations among other candidates.

William Negley, a candidate nearly as well-funded as Roy, highlighted the local roots of his money — including several prominent figures from his home town of San Antonio, such as businessman Red McCombs, who has donated $50,000 to a super PAC backing Negley.

“Texas likes local Texans,” he said. “I think it matters that you live and know where you aspire to represent.”

In a written statement, Roy brushed off the carpetbagging charges from his rivals, noting that he lives in the Hill Country region that makes up much of the 21st District, if not strictly within the district itself. “Voters are tired of games and want serious leaders to tackle the swamp, and that’s what we’re going to do,” he said.

Negley, a 34-year-old former CIA officer, is taking a slightly different tack in his campaign by focusing on national security and portraying himself as a “terrorist hunter” best equipped to combat threats abroad — a message he believes is honed for a district heavy on veterans and active-duty military families.

He said he is perfectly willing to advocate for standard conservative, small-government positions. “But if I start talking about deregulation and lowering taxes, then all of a sudden I blur into the white noise of 17 other candidates who are just touting their generic broad-brush conservative principles.”

No candidate, however, is taking a more contrarian tack than Jenifer Sarver, an Austin public relations consultant and former official in the George W. Bush administration, who is unapologetically calling for a more inclusive GOP and more distance from Trump.

“My message is, this is a safe Republican seat, but if we elect in a primary somebody who is extreme right, that makes the centrist Democrat candidate look a lot more appealing to people,” Sarver said. “There are moderates out there. They just have not had a voice.”

While key House forecasters have kept the 21st District in the Republican column, national Democratic Party groups have put the district on the midterm target list amid hopes it could flip if a wave materializes in November. One moderate Democratic candidate, tech entrepreneur and retired Army officer Joseph Kopser, has outraised all the Republican candidates.

Sarver said she has a shot in a race otherwise crowded with conservatives chasing the same votes. “I’ve been operating in my own lane,” she said. “They are slicing each others voters up.”

But she has faced sometimes brutal criticism from fellow candidates over her moderate views, her criticism of Trump’s incivility — and her unapologetic 2016 vote for Hillary Clinton.

At a Feb. 1 candidates forum in Buda, Tex., fellow candidates repeatedly attacked Sarver for voting for a Democrat. Businessman Matt McCall, the candidate with “MAGA” on his signs and a veteran of two unsuccessful runs against Smith, pressed Sarver on her calls to find common ground with Democrats.

Sarver rose to defend herself: “I see a party that’s aging and white, and that’s not the future of our country,” she said. “We have a tone that is shutting people out. Young people are not interested in joining our party, women are leaving our party in droves, and if you look out over this audience, it’s a very white crowd here tonight.”

Replied McCall, “We shouldn’t be getting along with the side that wants to kill babies.” He added: “Married women vote Republican. We don’t have a problem with women. We have a problem that people aren’t getting married in this country.”

Another candidate forum held Thursday in rural Kerrville helped Maggie Snow, 58, narrow the field of 18, but she said afterward she remained undecided.

“Lamar Smith really did help us, and truly represented the constituents,” she said, while also acknowledging “mixed feelings” about Trump — and how the congressional candidates are approaching him.

“I’m sure there’ll be a runoff,” she said, “so I’ll have to choose then.”

Moravec reported from Fredericksburg and Kerrville, Tex.