Rep. Dan Crenshaw's potential primary loss to state representative Steve Toth represents a stark warning sign for congressional Republicans deemed insufficiently loyal to President Donald Trump.The president has withheld endorsement despite backing 27 other Texas House Republicans, and Gov. Greg Abbott similarly bypassed him, but most damaging, Sen. Ted Cruz — after a tense airport confrontation — endorsed and campaigned for Crenshaw's challenger, reported CNN."The two famously brash Republicans had a tense exchange that now looms large over Crenshaw’s battle for political survival," the network reported. "Crenshaw accused Cruz of working against him in his House primary. According to three people with direct knowledge of their interaction, Cruz responded: 'If I’m working against you, you’re gonna know it.'"Cruz made good on that threat by recording an ad for a pro-Toth PAC that's now airing in the Houston area, and a source familiar with the president's thinking said Trump is not likely to back Crenshaw.“He told me he would — it’s up to him, he doesn’t owe me anything,” Crenshaw told CNN.The hostility stems from Crenshaw's heretical positions by MAGA standards: supporting Ukraine aid, certifying the 2020 election, and advocating for resettling Afghan allies. His personal conduct has compounded matters — a bitter feud with Tucker Carlson, Twitter provocations calling MAGA hardliners "grifters," and allegations of public drunkenness that Crenshaw denies.Yet Crenshaw's pro-Trump voting record remains firmly aligned with the White House. His actual policy positions don't justify the vendetta, but his crime is refusing to perform uncritical loyalty, maintaining independence on principle rather than pandering for endorsements.If Crenshaw loses Tuesday or in a May 26 runoff, he would be the first Texas House incumbent defeated in a primary since 2014 — a symbolic breaking point."Crenshaw's kinda got a Cornyn problem, in that he wasn't a devout Trumpy the whole time," said Texas GOP strategist Reb Wayne, "and now he's paying for it."Sen. John Cornyn (R-TX) faces his toughest reelection challenge from Trump-endorsed candidates questioning his loyalty. The pattern is explicit: Republicans demonstrating insufficient ideological purity face organized, well-funded primary challenges backed by Trump allies.Toth's campaign explicitly targets Crenshaw's Ukraine support and 2020 election certification vote, and a loss would signal to other Republicans what's expected in the Trump era to keep their standing with GOP voters.“He is not someone who just follows the party talking points and he has prided himself on telling the truth, including to Republican base voters, and sometimes they don’t like that,” said a person familiar with Crenshaw's thinking.