HARRISBURG, Pa. (AP) — Former U.S. Sen. Arlen Specter, the outspoken Pennsylvania centrist whose switch from Republican to Democrat ended a 30-year career in which he played a pivotal role in several Supreme Court nominations, died Sunday. He was 82.

Specter, who announced in late August that he was battling cancer, died at his home in Philadelphia from complications of non-Hodgkins lymphoma, said his son Shanin. Over the years, Arlen Specter had fought two previous bouts with Hodgkin's disease, overcome a brain tumor and survived cardiac arrest following bypass surgery.

Specter rose to prominence in the 1960s as an aggressive Philadelphia prosecutor and as an assistant counsel to the Warren Commission, developing the single-bullet theory that posited just one bullet struck both President Kennedy and Texas Gov. John Connally — an assumption critical to the argument that presidential assassin Lee Harvey Oswald acted alone. The theory remains controversial and was the focus of Oliver Stone's 1991 movie "JFK."

In 1987, Specter helped thwart the Supreme Court nomination of former federal appeals Judge Robert H. Bork — earning him conservative enemies who still bitterly refer to such rejections as being "borked."

But four years later, Specter was criticized by liberals for his tough questioning of Anita Hill at Clarence Thomas' Supreme Court nomination hearings and for accusing her of committing "flat-out perjury." The nationally televised interrogation incensed women's groups and nearly cost him his seat in 1992.

Specter, who had battled cancer, was Pennsylvania's longest-serving senator when Democrats picked then-U.S. Rep. Joe Sestak over him in the 2010 primary, despite Specter's endorsements by President Barack Obama and other Democratic leaders. Sestak lost Specter's seat to conservative Republican Rep. Pat Toomey by 2 percentage points.

A political moderate, Specter was swept into the Senate in the Reagan landslide of 1980.

He took credit for helping to defeat President Clinton's national health care plan — the complexities of which he highlighted in a gigantic chart that hung on his office wall for years afterward — and helped lead the investigation into Gulf War syndrome. Following the Iran-Contra scandal, he pushed legislation that created the inspectors general of the CIA.