The Wall Street Journal's conservative editorial board wasn't happy with President Donald Trump on Tuesday, warning he's about to repeat the political catastrophe that cost Republicans control of the Senate five years ago.In a sharply worded editorial published Tuesday, the Journal's editorial board argued that Trump's last-minute endorsement of Texas Attorney General Ken Paxton over Sen. John Cornyn in next week's GOP runoff puts the Texas Senate seat in play and effectively hands Democrats a path to flipping the chamber."In January 2021, Republicans needed to hold a pair of Georgia seats to keep their Senate majority. But President Trump divided the GOP with his claims that weak Republicans had cost him the presidential race, GOP turnout fell, and Democrats narrowly won both races. Is he trying to make the same mistake again?" the board asked.The Journal noted that Paxton was "impeached by his own party and has a history of personal and political scandals.""Many Republicans may stay home rather than vote for him, and we understand the impulse," the board lamented. The endorsement has already triggered an internal revolt. Senate Republicans were described as "livid" and "speechless" on Tuesday after Trump blindsided the conference. Trump took direct shots at Cornyn in his Truth Social post, calling him insufficiently loyal even though Cornyn has voted with Trump 99% of the time across both presidential terms.The Journal delivered a blunt assessment."If Mr. Paxton wins next week and Texas ends up being the seat that turns Senate control to the Democrats, Mr. Trump will deserve 'COMPLETE AND TOTAL' credit, as he likes to put it," the board concluded.The endorsement caps months of MAGA pressure that forced Trump's hand after he had initially planned to back Cornyn, with grassroots activists openly celebrating the prospect of purging a Senate Republican even at the cost of losing the seat.