Paxton / Cornyn, another GOP primary disaster?

20 May, 2026

President Trump endorsed Ken Paxton in his Texas Republican Senate primary yesterday against incumbent Senator John Cornyn. Already an underdog, Cornyn's chances of winning the primary dropped to just 6% on the betting markets after the endorsement. Some notes:

1. Paxton is a poor general election candidate, with a laundry list of political and personal scandals. He is roughly a coin-flip right now against Democrat James Talarico on the betting markets, but almost everyone believes that (a) Cornyn would have cruised to reelection and (b) it is going to take a huge financial investment by the GOP to get Paxton over the top.

2. This phenomenon—Republican primary voters choosing poor general election candidates in races against either shoe-in or highly competitive general election candidates, who then went on to lose in the general election—has plagued the GOP for over 15 years now. There are at least 10 instances of this happening in GOP primaries since 2010¹:

• Christine O'Donnell defeating Mike Castle (DE, 2010), lost to Christ Coons
• Sharon Angle defeating Sue Lowden (NV, 2010), lost to Harry Reid
• Ken Buck defeated Jane Norton (CO 2010), lost to Michael Bennet
• Todd Akin defeated John Brunner (MO, 2012), lost to Claire McCaskill
• Richard Muordock defeated Dick Lugar (IN 2012), lost to Joe Donnelly
• Roy Moore defeated Luther Strange (AL 2017), lost to Doug Jones
• Don Bolduc defeated Chuck Morse (NH 2022), lost to Maggie Hassan
• Blake Masters defeated Jim Lamon (AZ 2022), lost to Mark Kelly
• Herschel Walker defeated Gary Black (GA 2022), lost to Raphael Warnock
• Mehmet Oz defeated David McCormick (PA 2022), lost to John Fetterman

3. This has hurt the GOP in the Senate, particularly in 2022, when winning even two of the four winnable races would have given them a Senate majority. Instead, the Democrats had a 51-49 majority in the 118th Congress. This year, losing Texas could be the difference between holding the Senate and losing it.

4. The Castle loss is one I will never forget. Castle was very popular in Delaware, and had already won there statewide for both the governorship and his House seat. He was a big favorite to win the Senate election. I knew Castle very casually, and about a year after he lost to O'Donnell I saw him on the street near the Capitol. We started chatting and at one point I just involuntarily blurted out, "I cannot believe you aren't a U.S. Senator right now." To which Mike responded, "Me neither!"

5. There really isn't much in the way of analogs to this on the Democratic side. Joe Sestak defeated Arlen Specter in 2010, but Specter had switched parties from the GOP to avoid a primary fight there, so it was a very different dynamic. Sestak lost to Pat Toomey; arguably Specter would have been a stronger Dem candidate. But overall, this is asymmetric problem. Democrats have done a better job protecting their strong general election candidates from goofy leftwing challenges than the GOP has done on the right.

6. Why this plagues the GOP is an interesting question. The mechanism isn't a mystery. Turnout in primary elections is barely 20%, and those who do turn out tend to be much more ideologically committed, both on policy positions and against establishment-coded compromisers. For individual primary, it may even just be a rational expected value play. Party professionals put a high value on winning at all costs, but activist voters may prefer a lower chance of winning if the value is higher when you do win. A 25% chance with a "true conservative" can pencil-out as better than a 75% chance with someone they see as no different than the Democratic candidate.

7. Undoubtedly, Trump has played a big role in this since 2016. Not only is he an example of a party-crasher who has been successful—giving primary voters a reason to hope his secret sauce is transferable—but he has also personally intervened on behalf of a lot of the loser candidates, especially in 2022. Trump has seemingly never much cared about the GOP as a party but he obviously has an extremely strong connection to GOP primary voters. As we have seen this week in Louisiana and Kentucky, that makes his endorsement decisive in many cases. But doesn't help in the general election if he's not endorsing the strongest candidates, or is just making the endorsements out of vengeance.² This is not sitting well with Republican senators.

8. Another aspect of this is the conservative media ecosystem, whose goals pretty sharply diverge from the party professionals. Conservative talk radio and cable TV has significant incentives to not have the GOP in power; ratings are better and the message is simple when you are the opposition. Grievance politics is a lot easier to sell than governance choices. This has created a spiral where conservative media drives a lot of attention to extreme candidates, who then lose, which sets up the oppositional grievance politics, which promotes extreme candidates. Rinse and repeat.

9. All of this is somehow related to the famous Thomas Massie quote, which obviously has newfound meaning with his primary defeat last night at the hands of a Trump-back challenger:

"All this time," Massie explained, "I thought they were voting for libertarian Republicans. But after some soul searching I realized when they voted for Rand and Ron and me in these primaries, they weren't voting for libertarian ideas—they were voting for the craziest son of a bitch in the race. And Donald Trump won best in class, as we had up until he came along."

10. An underrated aspect of all this is what it is going to do to the Senate GOP caucus for the rest of the 119th Congress. You can now add Cornyn and Cassidy to the list of un-whippable GOP Senators for the remainder of the year, they aren't going to be listening. Consequently, whatever the White House might have wanted to get out of the Senate is going to be that much tougher. Even absent legislative goals, the blowback is going to be real. Cassidy is already flexing his disdain at Trump by voting to take up a Senate resolution to pull the plug on the war in Iran, which he had previously rejected several times this year. Not a pleasant time to be in the White House Legislative Affairs shop.