Bill Cassidy Bio
William Morgan Cassidy (born September 28, 1957) is an American physician and politician who has served as the senior United States senator from Louisiana since 2015. A member of the Republican Party, he is often described as a moderate within his caucus. Since 2025, he has chaired the Senate Health, Education, Labor, and Pensions (HELP) Committee.
Before entering politics, Cassidy trained and worked as a gastroenterologist. He built a medical career in Louisiana focused on liver disease, uninsured care, and public health. His clinical background shapes much of his Senate work on health policy, mental health, and prescription drug reform.
Early Life and Background
William Morgan Cassidy was born in Highland Park, Illinois, on September 28, 1957, one of four sons of Elizabeth Cassidy and James F. Cassidy. He is of Irish and Welsh descent. The family moved to Baton Rouge, Louisiana, when he was an infant, and he grew up in the region that would later form the base of his political career.
He attended Louisiana State University, where he earned a Bachelor of Science in 1979. He continued at the LSU School of Medicine, completing his Doctor of Medicine in 1983. These early academic choices pointed him toward a long career in medicine before any public office.
Path to US Politics
After medical school, Cassidy completed an internal medicine residency at the University of Southern California and Los Angeles General Medical Center, finishing in 1987. He followed that with a hepatology-gastroenterology fellowship at the same institution, completed in 1989. He spent a year in Los Angeles as a liver specialist and internal medicine physician at the Cigna Medical Center before returning to Louisiana in 1990.
Back in Louisiana, Cassidy specialized in liver disease at the Earl K. Long Medical Center. In 1998, he helped found the Greater Baton Rouge Community Clinic, a nonprofit offering free dental, medical, mental health, and vision care to uninsured residents. After Hurricane Katrina, he led volunteers who converted an abandoned Kmart into an emergency health care facility. These community medical efforts helped build the public profile that led him toward electoral politics.
Bill Cassidy Career
Early Career (2006-2009)
Cassidy was first elected to public office on December 9, 2006, winning a special election for District 16 in the Louisiana State Senate. He defeated veteran State Representative William Daniel and Libertarian S. B. Zaitoon, and was sworn in on December 20, 2006. In his first legislative term, he focused on health care access, hospital funding, and coastal issues tied to his medical and regional background.
He won a full four-year term on October 20, 2007, taking 76 percent of the vote against two minor-party challengers. The state senate experience gave Cassidy a platform on health policy and prepared him for a jump to federal office in 2008.
Breakthrough (2008-2014)
On November 4, 2008, Cassidy was elected to the U.S. House of Representatives from Louisiana’s 6th congressional district, defeating Democratic incumbent Don Cazayoux with 48 percent of the vote. He benefited from a strong independent candidacy that split the field, and he took office in 2009 as part of the freshman House Republican class.
He won easy reelections in 2010 and 2012, posting 66 percent and 79 percent of the vote, respectively. In the House, Cassidy built a record on earmark transparency, Gulf Coast energy policy, and Affordable Care Act opposition. He partnered with California Democrat Jackie Speier on earmark disclosure rules in 2009, and he introduced the Gulf Coast Jobs Preservation Act in 2010 in the wake of the BP oil spill. He also pushed the Energy Consumers Relief Act of 2013 to require cost-impact review of major Environmental Protection Agency rules.
In 2014, Cassidy ran for the U.S. Senate and defeated three-term Democratic incumbent Mary Landrieu in a runoff, 56 percent to 44 percent. It was the first Republican victory in that Louisiana Senate seat since 1883, and it marked Cassidy’s breakthrough into the upper chamber.
Republican Senate Era (2015-Present)
Since January 2015, Cassidy has represented Louisiana in the U.S. Senate. He was reelected in 2020 with 59.32 percent of the vote. On health care, he co-sponsored the Graham-Cassidy bill in 2017 to repeal and replace the Affordable Care Act, drawing national attention after a televised exchange with Jimmy Kimmel over what Cassidy called the Jimmy Kimmel test for coverage of children with serious conditions.
He has also worked across the aisle on tax and parental leave policy. In 2019, he helped introduce the Gold Star Family Tax Relief Act, and later that year, with Senator Kyrsten Sinema, he proposed a bipartisan paid parental leave plan allowing new parents to advance their child tax credit for a $5,000 cash benefit. During the 118th Congress, Cassidy became ranking member of the Senate HELP Committee and worked with Chairman Bernie Sanders on bipartisan legislation to lower prescription drug costs and reform pharmacy benefit managers.
In 2021, Cassidy was one of seven Republican senators to vote to convict President Donald Trump of incitement of insurrection in his second impeachment trial. The Republican Party of Louisiana censured him hours later, and he was later praised by Democrats, including his predecessor Mary Landrieu. He has continued his focus on mental health care, vaccine policy, and bipartisanship, and in January 2025 he became chair of the Senate HELP Committee. In his opening remarks, he highlighted declining child literacy, dyslexia support, antisemitism on campuses, and federal retirement reform as committee priorities.
Notable Events and Milestones
Cassidy’s career-defining moment remains his 2014 Senate runoff upset of Mary Landrieu, which ended a 131-year Republican drought in that seat. He later cemented his independent streak by breaking with his party to convict President Trump in his second impeachment trial and to certify the 2020 Electoral College results after the January 6 attack on the Capitol.
Bill Cassidy Career Wins
Cassidy has compiled a steady record of election victories since entering politics, beginning with his 2006 state senate special election win. His wins have come in special elections, regular cycles, and high-profile runoffs at both the state and federal level.
Federal Election Highlights
Cassidy won his U.S. House seat in 2008 with 48 percent, expanded his margin in 2010 with 66 percent, and reached 79 percent in 2012. He then unseated Senator Mary Landrieu in the 2014 runoff with 56 percent, and secured a second Senate term in 2020 with 59.32 percent. His 2014 victory is widely regarded as one of the most significant Republican Senate wins in modern Louisiana history.
Other Wins and Achievements
Beyond elections, Cassidy has passed bipartisan legislation, including the Gold Star Family Tax Relief Act in 2019, and has helped drive HELP Committee bills on prescription drug pricing and mental health access. His medical and humanitarian work, from founding the Greater Baton Rouge Community Clinic to leading post-Katrina emergency care, has also been recognized within Louisiana civic life.
Bill Cassidy Family
Family Background and Lineage
Cassidy is one of four sons born to James F. Cassidy and Elizabeth Cassidy. He is of Irish and Welsh descent. The family relocated from Highland Park, Illinois, to Baton Rouge, Louisiana, while he was still an infant, and Louisiana has remained his home base.
Personal Life
Cassidy married Laura Layden on September 29, 1989. Laura Cassidy is also a physician, and the couple met during their residencies in Los Angeles. Both worked at the Earl K. Long Medical Center in the early 1990s, where Laura served as head of surgery. They have three children and are members of The Chapel on the Campus, a nondenominational Christian church on the Louisiana State University campus in Baton Rouge.