ALLEN, Texas (AP) — President Donald Trump on Tuesday endorsed Texas Attorney General Ken Paxton, supercharging his effort to oust incumbent Sen. John Cornyn in a Republican primary runoff.

"Ken is a true MAGA Warrior who has ALWAYS delivered for Texas, and will continue to do so in the United States Senate," Trump wrote on social media.

When news of the endorsement broke, Paxton supporters began cheering and dancing to "YMCA," a Trump campaign anthem, at an event in Allen, Texas, where the attorney general was scheduled to speak.

Paxton and Cornyn qualified for the May 26 runoff after a March 3 primary, while Rep. Wesley Hunt finished third and did not advance.

Although the four-term Cornyn has backed Trump's agenda in Washington, Paxton pitched himself as a political warrior for the Make America Great Again movement. Trump's endorsement puts him at odds with his party's establishment, which is convinced that Cornyn is the better candidate for November's general election. The Democrats nominated Texas State Rep. James Talarico as their candidate for Senate.