How Louisiana’s Primary Was Rigged to Oust a Senator

Ideological donors and activists rewrote Louisiana’s rules to bring back partisan primaries, a system they can more easily dominate than the all-candidate primary the state used for half a century. A report from Unite America Institute found that when ideological PACs rally behind an alternative primary candidate to the party and business establishment, their candidates are about four times more likely to win. This outsized influence nearly disappears in all-candidate primaries, which is why ideological groups and donors prefer partisan primaries. 

Ideological PACs worked to reinstitute partisan primaries in Louisiana so they could target Sen. Bill Cassidy. If current polls hold, Cassidy will be the latest victim.

Sen. Cassidy, a reliable conservative by most measures, made himself a target when he voted to convict Trump in the second impeachment trial. Louisiana’s Republican Legislature responded by passing a law (authored by a lawmaker who then entered the race against Cassidy) that switches Louisiana's all-candidate (“jungle”) system to a closed partisan primary.

Gov. Jeff Landry, who has opposed Cassidy since the impeachment vote, signed it. A two-year delay was written into the bill, timed precisely for Cassidy’s 2026 race. As Lt. Gov. Billy Nungesser put it: “I think the real push for this was to beat Bill Cassidy for Senate. Let’s call it like it is.” Senate President Cameron Henry (R) suggested the legislature will likely reverse the change after the 2026 election.

How did Louisiana get here? And why does changing the primary system benefit those who wish to unseat Bill Cassidy?

The answer lies in the structure of the electorate. In a closed partisan primary, candidates are competing for a smaller, more ideologically sorted pool of voters. That makes the race easier for a well-funded faction to influence. In an all-candidate primary, by contrast, every candidate competes before a broader electorate, including independents and voters from outside the dominant party, making it harder for ideological donors to dictate the outcome.

For five decades, Louisiana didn’t have party primaries. All candidates ran on the same general election ballot, and if nobody won a majority vote, the top two finishers advanced to a runoff. Unite America Institute found that this system inspired more meaningful voter participation (822,000 no-party voters could vote without registering with a party), improved governance, promoted bipartisanship, and rewarded problem solving. Furthermore, all-candidate primary systems like the one used in Louisiana diminish the influence of the ideological PACs by roughly 75%.

In 1992, the biggest primary spenders were party committees, business associations, and labor unions — groups representing large numbers of voters, workers, professionals, or businesses. They would give 90% or more of primary dollars to incumbents, rarely backed primary challengers, and often supported both parties. Their money often flowed toward candidates seen as viable in the general election—particularly in competitive states where nominating a weaker or more ideological candidate could hand the seat to the other party.

Now, ideological Super PACs funded by a handful of ultra-wealthy donors are far more likely to back primary challengers, take risks in competitive states, and prioritize ideological purity over electability.

The Cassidy race illustrates the growing dominance of ideological donors and activists in party primaries like the one Louisiana adopted in 2026. The MAHA PAC pledged $1 million to challenger Julia Letlow shortly after she received an endorsement from President Trump, targeting Cassidy specifically for his pro-vaccine record. Letlow’s allied super PAC is running ads consistent with the ideological challenger playbook. Meanwhile, Cassidy has roughly $26 million in business community backing — but head-to-head polling in a Republican runoff shows Letlow leading 57–22.

This race reveals that ideological groups are fully aware that party primaries enhance their power, which is why they worked to change Louisiana's long-standing all-candidate primary system. Louisiana’s former system made the electorate larger, more diverse, and harder for a single ideological faction to dominate. Closing the primary does the opposite: it narrows the electorate, raises the value of ideological money, and gives organized factions a clearer path to replacing incumbents. In open, all-candidate primaries, the impact of support from ideological PACs on a candidate's primary vote share is one-quarter as strong as it is in party primaries.

Their playbook is clear:

• Step 1: Close the primary
• Step 2: Recruit a primary challenger
• Step 3: Enlist wealthy ideological donors

All-candidate primaries are the most effective tool that can be used against this playbook. They significantly blunt the power of ideological PACs by expanding the electorate beyond the small, low-turnout party primary universe where wealthy ideological factions have the greatest leverage.

The Cassidy race is not just a fight over one senator. It is a test case for whether ideological donors can change the rules, narrow the electorate, and then use that smaller electorate to remove an incumbent they could not as easily defeat under an all-candidate system.

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