The death of Chief Justice William Rehnquist late on Saturday ends his historic 33-year career on the Supreme Court and presents President George W. Bush with a rare challenge to fill a new vacancy just as John Roberts Jr., his nominee to Sandra Day O’Connor’s seat on the Court, was about to face Senate hearings.

Bush answered part of that challenge swiftly, nominating Roberts on Monday to replace Rehnquist as chief justice. In an early morning announcement from the Oval Office, the president said he hoped the Senate would confirm Roberts before the Court sits for its next term Oct. 3.