a major figure in american politics has died. Arlen specter served 30 years in the u.S. Senate playing a pivotal role in so many legal battles and confirmation dramas. Here tonight jon karl now.... See More
a major figure in american politics has died. Arlen specter served 30 years in the u.S. Senate playing a pivotal role in so many legal battles and confirmation dramas. Here tonight jon karl now. Reporter: He was a native of kansas but chose pennsylvania to be his home. After law school at yale he settled in philadelphia. Eventually becoming district attorney. After the kennedy assassination, sector served on the warren commission and helped develop the single-bullet theory. Specter was elected to the senate as a republican in 1980 becoming a fiercely independent centrist and a powerful voicen the josh elliott committee and infuriated his own party by helping to sink robert bork's nomination.Ge bork, with all due respect, I think you're putting the rabbit in the hat. Reporter: His tough grilling of anita hill angered democrats. I object to that vociferously. I'm asking questions here. Reporter: And helped lift clarence thomas to the high court. In 2009 he again infuriated republicans by supporting president obama's $800 billion stimulus bill. He lost the support of his party and became a democrat, but pennsylvania democrats didn't return the favor, and he lost his bid for a sixth term in the democratic primary. Specter battled cancer in 2005 and again in 2008, working in the senate through it all. That and another battle with a brain tumor made him a passionate advocate for medical research including stem cell therapy. Arlen specter lost his final battle with cancer at the age of 82. Jonathan karl, abc news, new york.
This transcript has been automatically generated and may not be 100% accurate.