Arlen Specter (born February 12, 1930) is a former United States Senator from Pennsylvania. Specter is a Democrat, but was a Republican from 1965 until switching to the Democratic Party in 2009. Elected to the Senate in 1980, Specter staked out a spot in the political center.
Specter was born in Wichita, Kansas to a Russian immigrant father and graduated from the University of Pennsylvania. He later served with the United States Air Force during the Korean War, graduated from Yale Law School, and opened a law firm with Marvin Katz, who would later become a federal judge. Additionally, Specter served as assistant counsel for the Warren Commission investigating the assassination of John F. Kennedy and helped devise the "single bullet theory." In 1965, Specter was elected District Attorney of Pennsylvania, a position that he would hold until he lost his re-election bid in 1973. In 1980, Specter was elected for the first time to the U.S. Senate for Pennsylvania.
On April 28, 2009, Specter announced that, after 44 years as an elected Republican, he was switching membership to the Democratic Party, however saying later that "he did not leave the Republican party, the party left ." On May 18, 2010, Specter was defeated in the Democratic primary by Joe Sestak. He was replaced by current Senator Pat Toomey on January 3, 2011.