Former U.S. senator and current "Law & Order" star Fred Thompson is stepping back into the political fray, accepting a position as an adviser to President Bush's Supreme Court nominee.

Thompson, a Republican who served one full term and part of another in the Senate, will serve as an informal adviser during confirmation hearings in the Senate. The White House says he accepted the post after speaking with the president on Monday (July 4), according to the AP.

The vacancy on the high court was created by Justice Sandra Day O'Connor's announcement last week that she was retiring. Her decision surprised most who follow the Supreme Court; many expected the next justice to leave would be Chief Justice William Rehnquist, who is fighting thyroid cancer.

Thompson was a congressional lawyer during the Watergate hearings in the 1970s and later pursued acting, appearing in such films as "Die Hard 2," "The Hunt for Red October" and "Barbarians at the Gate." He won a 1994 special election in Tennessee to fill the Senate seat vacated by then-Vice President Al Gore and was re-elected in 1996. During his tenure, he served on the Senate Judiciary Committee, which will hold the confirmation hearings on Bush's nominee.

It's unclear for now whether Thompson's role in the confirmation process will affect his work on "Law & Order," where he plays District Attorney Arthur Branch. He typically appears in just a few scenes per episode, and the show's writers could probably work around his absence if the confirmation and production schedules clash.