Ken Paxton defeats John Cornyn in Texas race, setting up a November election that could decide control of the US Senate.

Texas Attorney General Ken Paxton, boosted by President Donald Trump’s endorsement, has defeated four-term US Senator John Cornyn in the Republican Senate primary run-off, according to US media projections.

The result, quickly called by Fox News and CNN after polls closed on Tuesday, highlighted Trump’s continuing influence over the Republican Party and dealt a major blow to the party establishment in Washington, DC.

Cornyn, a longtime establishment conservative and former Republican whip, had represented Texas in the Senate since 2002 and entered the race as the favourite, backed by major donors and senior Republican figures.

But the senator struggled to connect with Trump’s political base.

Cornyn had previously criticised Trump and angered some conservatives by supporting bipartisan gun legislation after the 2022 Uvalde school shooting, while Paxton presented himself as one of Trump’s strongest allies.

Trump’s backing reshaped the race, making Cornyn the latest Republican incumbent to lose after falling out of favour with the president.

“Tonight, we’ve come up short,” Cornyn told reporters after the race was called.

“I’ve always supported the Republican ticket,” he said, adding that he intended “to do so again”.

The defeat makes Cornyn the first Republican senator from Texas to lose his party’s nomination for re-election and is likely to end his Senate career next year.

“Tonight, we just made history,” Paxton told cheering supporters, praising Trump’s endorsement as “the most powerful force in politics”.

This month, Trump’s endorsement of Republican primary challengers ousted incumbents including Louisiana Senator Bill Cassidy and Kentucky Representative Thomas Massie.

Controversies and midterm race

Paxton has spent years facing legal, ethical and personal controversies, including a 2023 impeachment by the Republican-led Texas House of Representatives, allegations of bribery and misconduct, and a high-profile divorce.

The 63-year-old was later acquitted by the Texas Senate and has repeatedly dismissed the allegations against him as politically motivated attacks.

Paxton will now face Democratic state Representative James Talarico in a closely watched November race that could help decide control of the US Senate.

Talarico, 37, has attracted moderate and independent voters, while some Republicans privately fear Paxton could struggle in a general election despite his popularity with Trump supporters.

An internal Republican Senate campaign memo circulated last year warned that a Paxton nomination could give Democrats a rare opportunity to flip Texas and force Republicans to spend heavily defending a seat long considered safe.

“Without a shadow of a doubt, I will be the Democrats’ number one target in November,” Paxton said.

The candidate also predicted that Talarico is “going to raise more money than any Democrat in America”, and urged his followers to donate to his campaign.

“If Republicans lose this state, we lose the country,” Paxton warned.

Within minutes of Paxton being declared the winner of the Republican primary run-off for US Senate, the Democrat called him “the most corrupt politician in America” in a social media post.

“He embodies the broken system we’re running against,” Talarico wrote on X.

In another post, he invited Cornyn’s supporters to vote for him.

“You have a place in our campaign,” Talarico wrote.