Sen. Arlen Specter dead at 82

Arlen Specter, a pugnacious and prominent former moderate in the U.S. Senate who developed the single-bullet theory in President John F. Kennedy's assassination and played starring roles in Supreme Court confirmation hearings, lost a battle with non-Hodgkin lymphoma Sunday at age 82.

For most of his 30 years as Pennsylvania's longest-serving U.S. senator, Specter was a Republican, though often at odds with the GOP leadership. His breaks with his party were hardly a surprise: He had begun his political career as a Democrat and ended it as one, too.

Specter never had his name on a piece of landmark legislation. But he involved himself deeply in the affairs that mattered most to him, whether trying to advance Middle East peace talks or federal funding for embryonic stem cell research. He provided key votes for President Barack Obama's healthcare and economic stimulus bills.

"For over three decades, I watched his political courage accomplish great feats and was awed by his physical courage to never give up. Arlen never walked away from his principles and was at his best when they were challenged," said Vice President Joe Biden, with whom Specter often rode the train home from Washington, D.C., when Biden also served in the Senate.

Specter is survived by his wife, Joan, sons, Steve and Shanin, and four granddaughters.

The Associated Press contributed to this report.