The race will help determine whether Democrats can win back control of the US Senate for the last half of the Trump presidency.
Ken Paxton defeats John Cornyn in Texas race, setting up a November election that could decide control of US Senate.
Paxton, the likely Republican nominee, is considered less likely to fare well against Democratic nominee in midterms.
Trump's move dismayed Senate Republicans, many of whom have served with the Texan for decades.
US President Donald Trump endorsed Texas Attorney General Ken Paxton in the state’s Republican Senate primary shortly after early voting began in an increasingly personal and expensive run-off against incumbent Senator John Cornyn. “Ken Paxton has my Complete and Total Endorsement to be the next United States Senator from the Great State of Texas – KEN PAXTON WILL NEVER LET YOU DOWN!,” Trump said in a social media post on Tuesday. The timing of the move came as a shock, with early voting already...
Polls show mixed results, with Paxton and Cornyn in close battle against Democrat James Talarico.