The president's endorsement is a blow to longtime Sen. John Cornyn, whom Senate Republicans had begged Trump to support.

Trump said Cornyn was “very late” in backing him for the Republican presidential nomination and during the presidency itself.

President Donald Trump has endorsed Texas Attorney General Ken Paxton, supercharging his effort to oust incumbent Sen. John Cornyn in a Republican primary runoff.

Donald Trump will announce who he is backing in the Texas Senate race, which features Sen. John Cornyn and state Attorney General Ken Paxton.