Arlen Specter, moderate who rejected right wing
US senator Arlen Specter eventually rejected the Republican party when he found himself at odds with its 'extremist' views
Agence France-Presse in Washington
Arlen Specter, a moderate former US senator from Pennsylvania who played key roles in critical Senate battles but angered colleagues by switching from Republican to Democrat, has died.
Specter died on Sunday of complications from non-Hodgkin's lymphoma - a form of immune system cancer - at home in Philadelphia, his family said. He was 82.
The five-term senator was elected in 1980 as a Republican, but he was one of just three in the party to vote for President Barack Obama's stimulus plan in 2009.
After being labelled a pariah by conservatives, he defected to the Democratic Party, only to lose its primary in 2010, ending his long Senate career.
"As the Republican Party has moved farther and farther to the right, I have found myself increasingly at odds with the Republican philosophy and more in line with the philosophy of the Democratic Party," Specter said at the time. But he also tied the decision to his already faltering re-election bid, angering some Democratic voters.
Specter played a key role in several Supreme Court nominations, notably derailing the 1987 nomination of conservative Robert Bork to the dismay of many of his fellow Republicans.
But the unpredictable politician angered liberals four years later when he backed the conservative Clarence Thomas in 1991.
During president Bill Clinton's 1999 Senate impeachment trial, Specter joined the president's Democratic backers in declaring Clinton "not guilty".
Obama endorsed Specter during the senator's 2010 Democratic primary, but it wasn't enough and Pennsylvanians instead chose upstart congressman Joe Sestak, a retired vice admiral with appeal among core Democratic supporters.
Sestak lost to conservative Pat Toomey, and the seat stayed in Republican hands.
Obama said Specter brought "that same toughness and determination to his personal struggles", which included a brain tumour and heart bypass surgery, as well as his fight with cancer, which his doctors discovered had returned in 2005.
"Arlen fought that battle for seven more years with the same resolve he used to fight for stem- cell-research funding, veterans health and countless other issues that will continue to change lives for years to come," Obama said.
Senate Democratic leader Harry Reid, who served with Specter for 28 years in Congress, described his colleague as "a man of moderation; he was always passionate, but always easy to work with … America is better today because of Arlen Specter."
Republicans also paid tribute to their onetime colleague. Iowa's Chuck Grassley, elected to the US Senate the same year, praised Specter's "tenacity and willingness to fight hard" regardless of the challenge.
Specter, who was Jewish, was born on February 12, 1930 in Wichita, Kansas. His father, Harry, had little formal education; he sold fruit and blankets and ran a scrapyard. But son Arlen excelled in high school and eventually graduated from the Ivy League's University of Pennsylvania, then Yale Law School.
Early in his legal career, Specter served on the Warren Commission that investigated president John Kennedy's assassination and was behind the controversial "single bullet theory" - a key underpinning of the panel's finding that Lee Harvey Oswald was the sole gunman.
As a senator, he infuriated many Republicans for his support of abortion rights, refusing to cave in to a party line that was leaning ever further to the right.
This year, Specter released his memoir Life Among the Cannibals, which detailed his decision to support Obama's stimulus, how he was shunned by the Republican Party, and the rise of the far-right tea party movement.
"'Extremism' was no longer sufficiently extreme to describe what was going on," Specter wrote about the anti-incumbent wave that swept Washington in 2010. "The quest for ideological purity was destroying comity and compromise and bringing government to a standstill."