A last-minute presidential endorsement has turned a Senate runoff into something much messier than anyone expected.

Nobody saw this coming — not John Cornyn, not Mitch McConnell, and apparently not even Trump’s own Senate allies. When the president endorsed Ken Paxton for U.S. Senate just two days into early voting, he didn’t just upend a Texas runoff. He sent a message to the entire Republican establishment: the party still runs through him, and he’ll remind you whenever he feels like it.

Political analyst Ross Hunt, principal of Hunt Research in Dallas, called it “somewhat surprising” — but he was being polite. Cornyn himself had told reporters earlier that week that a Trump endorsement was off the table. “The ship had sailed,” Cornyn said. Then the ship came back.

“I think a lot of what seems to be motivating the president is his own political and policy aims… right now, the Republican Party is completely owned by President Trump, and I think he feels the strength of that.”— Ross Hunt, Hunt Research

For Paxton, the timing is either a miracle or a very well-timed gift. Hunt believes the attorney general was already the slight favorite heading into the runoff — runoff electorates tend to skew more ideologically conservative, which plays to Paxton’s base. But Trump’s thumb on the scale makes him the clear frontrunner now. Not a lock. But close.

Can Cornyn still pull it off?

In theory, yes. Hunt’s early-vote analysis found that Cornyn-friendly counties — places like Travis County and parts of South Texas — were turning out at roughly the same pace as the March primary, maybe slightly better. But “roughly the same” isn’t a comeback. Cornyn needs a surge, not a steady pace. He’d also need to absorb a significant chunk of voters who originally backed George P. Bush — voters who are now up for grabs and don’t obviously belong to either camp.

If Cornyn somehow pulls it out, Hunt is clear: that’s an upset. A real one.