At 79, Arlen Specter was a rare Republican voice. The Jewish lawmaker from Pennsylvania started as a Democrat but joined the Republicans at a time when party leaders promoted the idea of a “big tent” which could accommodate moderates and conservatives.
But during the Bush era, moderates had been consistently sidelined in favour of conservative voices.
Mr Specter was not only the last Jewish Republican in the Senate, he was also the last holder of the tradition of moderate conservatism represented by Jewish Republicans dating back to New York’s Jacob Javits. Republican Jewish activists expressed their disappointment with Specter’s move, although they did not dispute his claim that the party has been shifting to the right.
Mr Specter, a cancer survivor, has broken with his party on healthcare and on stem-cell research — he cited health issues as crucial to his decision to cross the political line. Specter has also taken an independent path on abortions and immigration reform, issues that conservative Republicans fought fiercely against.
He was born in Kansas to parents who had emigrated from Russia. He is known as a close ally of the Jewish community, although most of the Jewish constituency in his home state is traditionally Democratic.
As a leading senator and the former chairman of the Senate’s judiciary committee, Mr Specter took on the Bush White House over their decision to permit bugging without warrants.
On foreign policy, Mr Specter stood out as a strong believer in peace between Israel and Syria and in a rapprochement between Washington and Damascus.