Sen. Arlen Specter, R-Pa.
As chairman of the Senate Judiciary Committee, Republican Sen. Arlen Specter of Pennsylvania will preside over the confirmation hearings of President Bush's nominee John Roberts.

Specter, who was elected to the Senate in 1980, is also a senior member of the Appropriations and Veterans Affairs committees.

Born in Wichita, Kan. in 1930, Specter attended school in Russell, Kan. and moved to Pennsylvania in 1947 as a student at the University of Pennsylvania. From 1951 to 1953 he served in the U.S. Air Force. He later attended Yale Law School where he received his law degree in 1956.

Specter has been described as a tough adversary, who has made his way through politics bullying opponents rather than winning friends.

"No one will ever use the word 'Specter' and 'beloved' in the same sentence," G. Terry Madonna, of Franklin and Marshall College's Center for Politics and Public Affairs, told the NewsHour in 2004. "No one gets up in the morning and says, 'Gee, I'm having lunch with Arlen Specter' and look forward to it."

A moderate Republican, Specter supported the war in Iraq, but has clashed with President Bush over the Patriot Act and over what he sees as a need to increase federal funding of education and health care.

His independent streak, which included a notable vote of "Not Proven" during the impeachment trial of President Clinton, has often landed him in fights with more conservative members of his own party. During his race for a historic fifth term as senator, Specter faced a bruising primary fight that pitted him against U.S. Rep. Pat Toomey, who ran accusing Specter of being too liberal for most of Pennsylvania. It took a last-minute push by President Bush and others for Specter to narrowly win the Republican nomination. He would later cruise to reelection.

Specter, who is battling Hodgkin's lymphoma, has also urged the president to lift restrictions on embryonic stem cell research, perhaps the most personal issue on his political agenda.

"The scientists know more than the people in the White House. And the scientists tell us they have enormous potential to cure diseases like the one I'm suffering from," Specter told CBS in June.

A former Pennsylvania assistant attorney general and Philadelphia district attorney, Specter and his wife reside in Philadelphia.

-- Compiled by Kristina Nwazota for the Online NewsHour