Senate Majority Leader John Thune — and most of the GOP conference — was reeling today from President Trump's snap endorsement of Texas Attorney General Ken Paxton.

Why it matters: Thune called it Trump's "decision." But it's Thune's problem to pass Trump's agenda, with a trio of senators the president can no longer hurt.

• Sen. Thom Tillis (R-N.C.) has been unbowed since announcing his retirement in July 2025 after clashes with Trump.
• Sen. Bill Cassidy (R-La.) voted with Democrats today to advance an Iran war powers vote to debate.
• Sen. John Cornyn (R-Texas) has a runoff May 26 but will enter it with Trump backing someone else.

😓 Adding to Thune's degree of difficulty: a president sick of the Senate and its rules, and rank-and-file Republicans seething over Trump's knifing of Cornyn.

• "I don't understand. He [Paxton] is an ethically challenged individual," said Sen. Susan Collins (R-Maine).
• "I'm supremely disappointed," Sen. Lisa Murkowski (R-Alaska) said.

Driving the news: Trump's endorsement of Paxton came in the middle of his 10-day GOP revenge tour.

• Cassidy fell Saturday, failing to make the runoff in Louisiana's Senate primary.
• "Horrible Congressman Thomas Massie" (R-Ky.), as Trump called him, has his primary today.

What we're watching: The $72 billion reconciliation package will be the first test for the Senate's newly combustible environment.

• "I just came off the campaign trail. People love the president," Cassidy said. "But I can tell you, a billion dollars for the ballroom … that's not where their head is, and that's not where my head is."

Zoom out: Trump's relations with the Senate have sunk to new lows over his frustration with the Senate parliamentarian, Republicans' refusal to abolish the filibuster, and GOP handwringing over ballroom security funding.

• Thune pronouncing himself "not a big fan" of the new $1.76 billion Department of Justice "anti-weaponization" fund this morning could have been the final straw.

What they're saying: "He's done with the Senate bullsh*t and Thune and all of them. They can't deliver," said a Trump confidante.

• "The only reason the president was holding out for Cornyn was the SAVE Act," the confidante said. "And when that became a lost cause, it was 'Why the f*ck should I support this guy?'
• "[Trump] saw some polling this weekend.… The polling showed Paxton will win in November. It might have been Paxton's polling. But it's Texas," a Trump adviser said.

⚡️ Zoom in: GOP lawmakers have several must-pass bills in the next five months, followed by several nice-to-pass pieces of legislation.

• Trump is demanding money for ICE and Border Patrol before June 1. Section 702 of the Foreign Intelligence Surveillance Act expires June 12. The farm bill needs to pass by Sept. 30.
• Republicans are working to pass a housing bill to lower costs and looking for 60 votes on a bill to provide market structure for cryptocurrency.
• A reconciliation 3.0 package is still being discussed — with varying degrees of earnestness and snickering — in both chambers.

🙀 The bottom line: Trump has always enforced GOP loyalty with raw fear, naked threats and decisive punishment.

• Now he'll learn whether fear loses its hold on lawmakers who have already lost — or are staring at defeat.

— Hans Nichols, Kate Santaliz, Marc Caputo and Alex Isenstadt

House Democrats are ready to be a buzzkill against the explosion of AI in campaign ads if they retake the House in November.

• "I have had a number of conversation[s] with the AI community about the issue generally and about my bill to require disclosure of the use of AI in political ads," House Administration Committee ranking member Rep. Joe Morelle (D-N.Y.). told us.
• Morelle is House Minority Leader Hakeem Jeffries' top lieutenant on election policy.

Why it matters: AI helps campaigns save on the often prohibitive cost of producing ads. But some are using the new technology to push the limits of negative campaigning.

• One "satirical" ad in Kentucky's 4th district accusing Massie of being in a "throuple" with Reps. Alexandria Ocasio-Cortez (D-N.Y.) and Ilhan Omar (D-Minn.) includes phony, AI-generated videos of the three dining together, holding hands and checking into a hotel.
• Another ad in that race uses AI to depict Massie rival Ed Gallrein fleeing a Trump rally, changing his voter registration and abandoning Trump in a WWII-style foxhole — all without any apparent disclosure.

State of play: AI-generated ads and videos have begun to proliferate in federal, state and even local elections across the country.

• The NRCC has used AI to create deepfake videos of Senate Minority Leader Chuck Schumer and Texas state Rep. James Talarico reciting written comments.

The other side: A Democratic House candidate in upstate New York released an AI-generated video attacking Rep. Elise Stefanik (R-N.Y.) last July.

• Rep. Jasmine Crockett (D-Texas), who lost the Democratic Texas Senate nomination to Talarico in March, was accused of using AI to enhance a crowd in the closing shot of one of her ads.
• Jesse Jackson Jr., an unsuccessful House candidate in Illinois, used AI to enhance the voice of one of his endorsers, former Rep. Bobby Rush, whose vocal cords were damaged by throat cancer.

— Andrew Solender