St. Tammany Councilwoman Launches Historic Senate Challenge Against Bill Cassidy

LAFAYETTE, La. (KPEL News) — St. Tammany Parish Council member Kathy Seiden announced Wednesday she’s running for U.S. Senate, becoming the first woman to enter Louisiana’s 2026 Republican primary. She joins what’s already a crowded field trying to unseat Sen. Bill Cassidy.

According to The Advocate, Seiden launched her campaign with a six-minute documentary video titled “The Outsider.” She made a bold prediction: she’ll become only the fifth challenger since 2000 to defeat a sitting U.S. Senator in a party primary.

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“I’m running because Washington has lost touch with the real challenges families face every single day,” Seiden said. “As a mother of four, I’ve lived those struggles. We need a fighter who stands unapologetically for faith, family, and the American way of life.”

Who Is Kathy Seiden?

Seiden was born in Hammond and raised in Port Allen. She graduated from Episcopal High School in Baton Rouge, then earned a communications degree from LSU. She lives in Mandeville with her husband Daniel, a nuclear energy consultant, and their four children.

Her political resume is short. She won election to the St. Tammany Parish Council in 2023, representing District 4. She led the council’s Economic Development Workgroup and helps oversee the parish’s $160 million budget. That’s it.

But Seiden is turning that lack of experience into her main campaign message.

“I think voters are ready for someone they can relate to who understands what they go through every day, not another career politician,” Seiden told WDSU.

Before announcing, Seiden hired Adam Geller, a pollster who worked on all three of President Trump’s campaigns. According to NOLA.com, that hire shows she’s serious and has Trump-world connections.

The Republican Field Is Packed

Seiden is the ninth Republican to file for the race, according to FOX 8. Sen. Bill Cassidy is running for a third term after holding the seat since 2015.

The other major Republicans include Louisiana State Treasurer John Fleming, a former U.S. Representative who announced in December 2024. State Sen. Blake Miguez from Acadiana jumped in during June 2025. Public Service Commissioner Eric Skrmetta, who co-chaired Trump’s Louisiana campaigns, is also running.

Several other Republicans filed paperwork, including Randall Arrington, a retired Navy aviator and college professor, and Sammy Wyatt from LSU Health-Shreveport.

The field might get bigger. NBC News reports that U.S. Rep. Julia Letlow is thinking about running. Her late husband Luke Letlow won a congressional seat in 2020 but died from COVID-19 complications before taking office. Julia won the seat in a special election and her statewide name recognition could shake up the race. State Rep. Julie Emerson says she’ll only run if Letlow stays out.

No Democrats have filed yet.

Louisiana Changed How It Picks Senators

The 2026 Senate race uses a different system than Louisiana voters are used to. Gov. Jeff Landry signed House Bill 17 in 2024, ending the state’s jungle primary for the first time since 2010, according to Wikipedia.

Here’s how it works now: Republicans and Democrats vote in separate primaries on April 18, 2026. Unaffiliated voters can participate, but you can’t cross party lines. If nobody gets 50% in the primary, the top two candidates go to a runoff on May 30, 2026. The general election happens November 3, 2026, with a possible runoff December 12.

This matters for Cassidy. Under the old system, Democrats and independents could vote for the most moderate Republican—potentially helping Cassidy survive a conservative challenge. Now Cassidy has to win over Republican primary voters, the same people angry about his 2021 vote to convict Trump.

The Polling Shows Cassidy Has Problems

Cassidy’s numbers tell two different stories. A Ragnar Research poll from May 2025, reported by KTAL, found Cassidy with 44% favorable and 34% unfavorable among likely Republican voters. Forty-five percent said they’d vote for him. His favorability topped 40% across all demographics.

Morning Consult polling from April 2025 looked better, giving Cassidy a 69% approval rating among registered Republicans and 64% among conservatives. His campaign reported over $6.5 million in the bank.

But Fleming’s internal polling tells a different story. His February 2025 poll, reported by The Washington Examiner, showed Fleming at 29% among likely Republican primary voters, Cassidy at 27%, with 36% undecided. Head-to-head, Fleming led 40% to 27%, with 33% undecided.

Morning Consult’s January 2025 analysis noted Cassidy’s approval hit a four-year high, but he’s still weaker than Sen. John Kennedy and Gov. Jeff Landry. His “strong approval” sits at 27%—better than after the impeachment vote but not great.

Trump Loyalty Is the Only Issue That Matters

Every Republican in this race knows they need to prove they’re the most loyal to Trump.

According to The Advocate, each candidate is working their Trump angle. Fleming says he worked in the White House during Trump’s first term, “10 steps from the Oval Office.” Skrmetta ran Trump’s Louisiana campaigns. Miguez calls himself an “America First Conservative.”

Seiden hired Trump’s pollster and built her campaign around “MAGA” messaging. She’s going after voters who see Cassidy’s impeachment vote as betrayal.

Cassidy is trying to fix his Trump problem. At an August news conference, he pointed to his votes confirming Trump cabinet members Pete Hegseth, Robert F. Kennedy Jr., and Lori Chavez-Deremer. He talked about standing behind Trump when the president signed Cassidy’s fentanyl bill.

“I’m the only one who actually speaks to the president,” Cassidy told reporters.

But the impeachment vote won’t go away. Cassidy joined six other Senate Republicans voting to convict Trump after January 6, 2021. Louisiana Republicans haven’t forgotten.

What Comes Next

This race is a test of Trump loyalty in Louisiana’s Republican Party. Nine Republicans are running, maybe more coming. The April primary will be messy. Getting to 50% will be hard, so there’s probably a May runoff.

The closed primary helps conservative, Trump-aligned candidates. Democrats who might have voted for Cassidy as the moderate option can’t participate in the Republican primary anymore. That creates an opening for challengers like Seiden who can run as Trump loyalists without any history of opposing him.

NOTUS reported that Democrats are watching the Republican fight, hoping it creates an opening. The Democratic Senatorial Campaign Committee said “Republicans are careening towards a nasty primary in Louisiana, where Senator Cassidy’s popularity with the base is cratering.”

But Louisiana hasn’t elected a Democrat statewide in years. Even a wounded Cassidy or another Republican would win in November. The real battle happens in the Republican primary this April and possibly May.

Seiden needs to prove she’s credible against better-known candidates like Fleming and Miguez. Her “Outsider” documentary and emphasis on being a relatable mother instead of a career politician is her strategy for breaking through in a field of nine Republicans all claiming to be the real Trump conservative.

Voters will decide April 18, 2026. Louisiana now has its most crowded and contentious Republican Senate primary in years.