William Morgan Cassidy, born in Highland Park in 1957, bridges the intersection of clinical practice and national governance. A gastroenterologist by training, he leveraged his experience in public health initiatives in Louisiana into a multi-decade career in elective office, serving as both a United States representative and a three-term senator for the state of Louisiana.
Medical Background and Public Health Initiatives
Cassidy completed his medical education at the Louisiana State University School of Medicine in 1983, following a Bachelor of Science from the same institution. His clinical residency in internal medicine occurred at the University of Southern California and the Los Angeles General Medical Center, concluding in 1987. He further specialized through a fellowship in hepatology and gastroenterology. Returning to Louisiana in 1990, he provided care at the Earl K. Long Medical Center. His community involvement included founding the Greater Baton Rouge Community Clinic in 1998, a volunteer-run facility providing medical, dental, and vision services to the uninsured. Following Hurricane Katrina, he organized medical volunteers to convert an abandoned retail space into a functional emergency clinic.
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His entry into formal politics began with a special election in 2006 for the 16th district seat in the Louisiana State Senate, which he won to replace Jay Dardenne. During this period, he shifted his political affiliation from the Democratic Party to the Republican Party, citing his disapproval of public hospital inefficiencies. He secured a full four-year term in 2007 with 76% of the vote before transitioning to federal office.
Federal Representation and Senate Service
In 2008, Cassidy defeated incumbent Don Cazayoux to win a seat in the U.S. House of Representatives, representing Louisiana's 6th district. He held this seat until his 2014 victory over incumbent Senator Mary Landrieu. His Senate tenure involved committee assignments, including chairing the Health, Education, Labor, and Pensions Committee starting in 2025. Known as a moderate Republican, he diverged from party leadership by voting to convict Donald Trump during the second impeachment trial in 2021. He later declined to endorse Trump in the 2024 general election cycle. His tenure in the Senate ended following a loss in the 2026 Republican primary, where he finished third behind Julia Letlow and John Fleming.
Fast facts
- Born: 1957, Highland Park, Illinois
- Education: Louisiana State University, LSU School of Medicine
- Medical Specialty: Gastroenterology and hepatology
- Political Party: Republican
- State Senate Service: 2006-2009
- U.S. House of Representatives Service: 2009-2015
- U.S. Senate Service: 2015-2025
- Citizenship: United States
Questions readers ask
What medical initiatives did Cassidy lead in Baton Rouge?
He helped establish the Greater Baton Rouge Community Clinic in 1998 to assist uninsured patients and founded the Health Centers in Schools program to provide vaccinations.
Why did Cassidy change his political party affiliation?
He stated that he moved from the Democratic to the Republican Party due to the decline of conservative Democrats and his frustration with the bureaucracy of public hospital systems.
Achievements
- Held posts at Louisiana State University and LSU Health Sciences Center New Orleans
