William Morgan Cassidy, born September 28, 1957, in Highland Park, Illinois, is an American physician and Republican politician serving as the senior United States Senator from Louisiana since 2015. He earned a Bachelor of Science in biology from Louisiana State University in 1979 and a Doctor of Medicine from the LSU School of Medicine in 1983. Cassidy specialized in gastroenterology, working as medical director of endoscopy at Earl K. Long Medical Center and as a professor at LSU Health Sciences Center before entering politics. Elected to the Louisiana State Senate in 2005 (serving 2006-2009), he then won election to the U.S. House representing Louisiana's 6th district from 2009 to 2015. Previously, he served on the House Energy and Commerce Committee, focusing on public health policy during events like the COVID-19 pandemic. In the Senate, Cassidy has emphasized health care, education, and labor issues, serving as Republican Chair of the Senate Health, Education, Labor, and Pensions (HELP) Committee since 2025, where he has attempted to advance the Antisemitism Awareness Act while addressing concerns from conservative Christians.