Arlen Specter, the moderate Republican who became a Democrat, passed away at age 82.

Specter died Sunday from non-Hodgkin lymphoma, cancer of the lymphatic system, according to the Los Angles Times.

Specter made a name for himself as a prosecutor, but in 1980 he began his time in the Senate as a stern moderate. He became the longest-serving senator in the state of Pennsylvania with five consecutive terms.

In 2009, he upset Pennsylvania voters for his decision to switch from the Republican Party to become a Democrat. His reason behind the change was that he believed the Republican Party became too conservative for his tastes.

Specter's defection came before the 2010 Pennsylvania primary where a more conservative candidate for the position was likely to get the party's vote.

Specter explained his decision saying, "I am not prepared to have my 29-year record in the United States Senate decided by the Pennsylvania Republican primary electorate - not prepared to have that record decided by that jury."

Being a moderate turned out to be a hard stand to take as his re-election failed in 2010 when a more liberal candidate took the Democrat's vote from Specter.

Born in Kansas in 1930 to a Russian Jewish immigrant father, Specter left the state when he was 17 to study at the University of Pennsylvania. After graduating in 1951, he joined the Air Force and eventually studied at Yale Law School.

At age 35, he made his first party switch from Democrat to Republican in order to receive a nomination for Philadelphia's district attorney which he served between 1966 through 1974.

In 1996 Specter ran for President under the Republican ticket, but ultimately bowed out.

Specter had a number of health concerns that included the need for open-heart surgery, removal of a brain tumor and was treated for Hodgkin's lymphoma through chemotherapy.