Arlen Specter, a gruff, independent-minded moderate who spent three decades in the US Senate but was spurned by Pennsylvania voters after switching in 2009 from Republican to Democrat, died on Sunday of cancer, his family said. He was 82.
Specter played a pivotal role in many of the major issues of his time, including the investigation into the assassination of US president John F Kennedy, disputes over controversial supreme court nominees, and the Senate vote not to remove then US president Bill Clinton from office for perjury after an affair.
Specter had announced in August a recurrence of non-Hodgkin lymphoma, cancer of the lymphatic system. His son Shanin Specter confirmed his death in Philadelphia.
Resilient, smart and aggressive, the former prosecutor frequently riled conservatives and liberals on his way to becoming Pennsylvania’s longest-serving US senator.
He was elected to five six-year terms starting in 1980. He left the Republican Party because he said it had become too conservative.
“Arlen Specter was always a fighter. From his days stamping out corruption as a prosecutor in Philadelphia to his three decades of service in the Senate, Arlen was fiercely independent – never putting party or ideology ahead of the people he was chosen to serve,” said US president Barack Obama.
Former US president George W Bush said Specter “loved our country and served it with integrity”.
Republican presidential candidate Mitt Romney said Specter participated in some of the most “consequential and historic debates” of his time. “His fight against cancer served as an inspiration to others battling this deadly disease,” he said.
Specter steered a moderate course during an era when the two major US political parties became increasingly polarised, and often broke with his party.
His sometimes testy demeanour and opportunistic manoeuvring earned him monickers like “Snarlin’ Arlen” and “Specter the Defector”.
In 2009, Specter left the Republican Party after 44 years when he concluded he could not win his party’s primary in Pennsylvania in 2010 against a conservative challenger. But his bid for re-election in 2010 ended in failure when he was beaten by a liberal challenger for the Democratic nomination.
After Kennedy’s assassination in 1963, Specter served on the Warren Commission that investigated the shooting, and he helped devise the disputed “single-bullet theory” that supported the idea of a lone gunman.
During his lengthy Senate career, Specter was crucial in increasing US spending on biomedical research.
He helped get one conservative, Clarence Thomas, confirmed as a supreme court judge in 1991, while torpedoing the supreme court nomination of another conservative, Robert Bork, in 1987.
Specter annoyed fellow Republicans by voting “not proven” on impeachment charges against Mr Clinton in 1999, helping prevent him from being ousted from office over his affair with a White House intern.
Specter unsuccessfully sought the 1996 Republican presidential nomination.
He had several health scares, undergoing open-heart surgery and surgery for a brain tumour, as well as chemotherapy for two bouts of Hodgkin’s lymphoma.
In February 2009, a month after Mr Obama took office, he became one of three Republican senators to vote for his economic stimulus Bill that Specter said was needed to avert a depression like that of the 1930s.
Specter was reviled by some conservatives for giving Mr Obama an important early political victory.
In April 2009, at the age of 79, he abandoned the Republicans – saying his party had moved too far to the right – and was welcomed by Mr Obama and US vice-president Joe Biden as a Democrat.
Specter is survived by his wife and two sons.