William Morgan Cassidy is an American politician and physician who has served as Louisiana's senior United States senator since 2015. A member of the Republican Party, he previously served in the Louisiana State Senate (2006–2009) and the U.S. House of Representatives (2009–2015).
Raised in Louisiana after being born in Highland Park, Illinois, Cassidy earned a B.S. from Louisiana State University (1979) and an M.D. from LSU School of Medicine (1983). He trained in internal medicine and gastroenterology/hepatology at USC/Los Angeles General, then returned to Louisiana and became known for a “doctor-legislator” profile grounded in public health, clinics, and community medicine.
Outside government, Cassidy helped found the Greater Baton Rouge Community Clinic to expand free care for uninsured residents and supported school-based health initiatives (including vaccination programs). After Hurricane Katrina, he led volunteers in setting up an emergency care facility in an abandoned retail space, an episode that became central to his “practical service” brand.
In the Senate, Cassidy has built a reputation as one of the GOP’s more policy-forward operators on health, education, and workforce issues. He has chaired the Senate Health, Education, Labor, and Pensions (HELP) Committee since 2025, and he has worked at times across the aisle on mental health, addiction treatment, and prescription-drug / PBM-related reforms.
Politically, Cassidy is often characterized as a moderate Republican and has had recurring friction with the party’s hardline populist wing—most prominently after he voted to convict Donald Trump in the second impeachment trial (2021), which led to a state-party censure and sustained primary chatter. That intraparty tension is now sharpened by repeated 2026 challenges from the right in Louisiana’s Senate politics.
Moderate Republican
Caucus Memberships
Achievements
- Physician-led public service brand: helped found the Greater Baton Rouge Community Clinic to expand free care for uninsured residents.
- Built school-based health initiatives in East Baton Rouge Parish, including vaccination programs.
- Post-Katrina response: helped coordinate volunteers to establish emergency medical services for displaced residents.
- Senate policy footprint in health and workforce issues; chaired the Senate HELP Committee beginning in January 2025.
- Maintained a “fix-it” governing reputation in Louisiana politics, emphasizing infrastructure, disaster recovery, and coastal resilience.
Controversies
- One of seven GOP senators to vote to convict Donald Trump in the second impeachment trial, prompting a formal censure from the Louisiana Republican Party.
- Has been criticized by conservatives for public breaks with Trump, including urging him to exit the 2024 race after a classified-docs indictment and declining to endorse him in the general election.
- Drew scrutiny for high-profile ACA-related proposals (including the “Graham–Cassidy” effort) and for contentious claims during the repeal/replace era.
- Comment on Louisiana maternal mortality and race (2022) drew backlash for framing disparities in a way critics said minimized systemic factors.
- Faced cross-pressures as a pro-vaccine physician during high-salience fights over federal health leadership and vaccine policy.
Top Donors
| Donor | Total | Individuals | PACs |
|---|---|---|---|
| Ochsner Health System | $244,790 | $244,790 | $0 |
| Welsh, Carson et al | $218,580 | $218,580 | $0 |
| Cajun Industries | $173,650 | $173,650 | $0 |
| Edison Chouest Offshore | $130,700 | $130,700 | $0 |
| B&G Food Enterprises | $124,235 | $124,235 | $0 |
Amounts shown reflect organization-linked giving; most funds listed here are from individual donors or aligned PACs.
Recent Elections
2014 Margin R +11.9%
2020 Margin R +39.0%