By Nolan D McCaskillWashington ― Texas attorney-general Ken Paxton ousted four-term US senator John Cornyn, riding President Donald Trump’s endorsement to a runoff victory for the Republican Senate nomination, US media projected.The race results were called shortly after polls closed in Texas’ westernmost counties on Tuesday, which are in a separate time zone from most of the state.“Without a shadow of a doubt, I will be the Democrats’ No 1 target in November,” Paxton said in his victory speech. “Texas will be the radical left’s No 1 priority, but ... we’re not going to let them take it.”Paxton’s win will force Cornyn into retirement early next year and the Republican political establishment in Washington into embracing a candidate it has long opposed.High-profile raceCornyn, 74, was backed by Republican leadership in the fight of his political life against Paxton, a 63-year-old, scandal-plagued attorney-general who won Trump’s endorsement last week.Paxton will face Democratic state Representative James Talarico in a high-profile race that could help decide control of the Senate and may become one of the most expensive in US history.The 37-year-old Democrat is a Presbyterian seminarian and leading fundraiser whose campaign has appealed to independent and moderate voters. Paxton’s supporters quickly attacked his past comments about a nonbinary God and six biological sexes, with Paxton and the Republican National Committee chair calling him “Tala-freak-o”.Senate Republicans’ campaign arm warned in an internal memo last year that a Paxton nomination “would hand Democrats an opening to flip Texas and cause Republicans to divert hundreds of millions of dollars that would otherwise be spent winning key battlegrounds.”Trump congratulated Paxton in a social media post on Wednesday and promised to hold “some nice, big, beautiful rallies” for him, writing: “Texas, this will be FUN!”Cornyn told supporters he will back the Republican ticket in November.“I’ve said throughout this race that I trust the voters of Texas, and they made their decision, and I must respect it,” he said in his concession speech.Republicans hold a 53-47 majority in the Senate over Democrats, who would need to net four seats in November’s election to take control of the chamber. Democrats are on defence in two states Trump won in 2024 ― Georgia and Michigan ― but could win the chamber by holding those two seats and flipping North Carolina, Maine, Ohio and Alaska.A competitive race in Texas, where no Democrat has won statewide since 1994, would expand the party’s path to a majority and potentially force Republicans to redirect investments from more competitive battlegrounds to protect their nominee in a state that Trump carried by nearly 14 percentage points in 2024.Loyalty over electabilityIn backing Paxton, Trump chose loyalty over electability as he continues to flex his iron grip over Republican voters. This month, Trump’s endorsement of Republican primary challengers ousted incumbents including Louisiana Senator Bill Cassidy and Kentucky Representative Thomas Massie.Paxton was impeached by the Texas House, indicted for felony fraud, reported to the FBI by his top aides and is being divorced by his wife on biblical grounds, though he has denied any wrongdoing.In a joint statement, Democratic senators Chuck Schumer and Kirsten Gillibrand said, “Republicans are facing their nightmare scenario” while Democrats move closer to winning the majority.Lauren French, a spokesperson for the Democratic Senate Majority PAC, said Paxton’s win was a loss for Washington Republicans, who spent nearly $100m on Cornyn’s behalf.“Even members of his own party call Paxton too corrupt and too damaged for Texas. Now he’s the GOP standard-bearer,” she said. “Good luck with that.”Talarico starts the general election with a three-month head start after defeating US Representative Jasmine Crockett on March 3.In a new campaign video released on Tuesday night, Talarico said, “The most corrupt politician in America just became the Republican nominee for US Senate.”Talarico’s initial lead in the opinion polls has evaporated, with the most recent survey showing the race in a dead heat against Paxton, with 8% of likely voters undecided.Cornyn’s campaign attacked Paxton’s character from the beginning, including calling him “Crooked Ken” and launching a dating game that allows users to swipe on Paxton’s alleged mistresses.Paxton challenged Cornyn to stop the negative ads “for the good of our party”.“We have already changed our TV ad traffic ... to ensure our campaign ends on a positive note (so) that we can focus on beating the leftist lunatic in the fall,” Paxton wrote on X last week.Voters across the state also chose their nominees in more than a dozen congressional districts, including the San Antonio-area 35th district, an open seat Democrats are hoping to flip.Trump-endorsed US Air Force veteran Carlos De La Cruz defeated Republican state Representative John Lujan.The Democrats’ preferred candidate also prevailed. Johnny Garcia, a public information officer for Bexar County Sheriff Javier Salazar, beat Maureen Galindo, a fringe candidate who has been widely condemned for antisemitic comments.Garcia won despite a Republican-aligned political committee called Lead Left PAC spending nearly $1m boosting Galindo.