Arlen Specter, the outspoken senator who started off Republican, switched to Democrat and stayed moderate throughout, has died, the AP reports.

The former five-term senator from Pennsylvania announced that he was once again battling cancer in August. He died at his home in Philadelphia on Sunday, according to his son, Shanin, from complications of non-Hodgkins lymphoma.

As NPR's Nina Totenberg reports for our Newscast desk, for 30 years Specter was among the most influential and controversial members of the Senate:

"Reviled by the right, mistrusted by the left, Specter was nonetheless a major force on matters of policy and politics. For the GOP, his cardinal sin was his leadership role in opposing the Supreme Court nomination of Robert Bork, a role he said he never regretted.

"'Judge Bork had a view of the constitution that was different from anybody else that'd ever been nominated to the Court,' Specter said. 'He could have turned the Constitution upside down.'

"For the left, his sin was his attack on law professor Anita Hill when she testified that Supreme Court nominee Clarence Thomas sexually harassed her.

"'It is my legal judgment that the testimony from Prof. Hill was flat-out perjury,' he said.

"Years later, Specter would say there was no way to know whether Thomas or Hill was telling the truth."

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Source: NPR