President Donald Trump on Tuesday endorsed Texas Attorney General Ken Paxton in his primary challenge to Sen. John Cornyn, dealing a massive blow to the incumbent with major implications in the fight for the Senate majority.

Unusually for a race of this size, Paxton allies are pointing the finger at a single donor: Leonard Leo, the conservative powerbroker.

Sen. John Cornyn does not believe President Donald Trump will make an endorsement in his competitive primary runoff against Ken Paxton.

Republicans are worried they’ll lose the Senate after Trump backed Ken Paxton.

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