Mr. Bush urged senators to confirm Roberts before the court session resumes Oct. 3 and said he was considering many candidates for filling a second vacancy. "The list is wide open," Mr. Bush said.
The president also sent a written notice to the Senate nominating the 50-year-old Roberts as chief justice and withdrawing his earlier nomination as an associate justice to succeed Sandra Day O'Connor. She is retiring but remaining on the bench until her replacement is confirmed.
Senate leaders made the hearings announcement Tuesday as Rehnquist's body lay in repose across the street at the Supreme Court. Roberts, a former Rehnquist clerk, helped carry the flag-draped casket into the building for public viewing.
Senate Judiciary Chairman Arlen Specter, R-Pa., said senators on the panel would begin their opening statements at noon on Monday. Roberts would be likely to make his opening statement late that afternoon after being introduced by Indiana Sens. Richard Lugar and Evan Bayh, and Virginia Sen. John Warner.
Roberts is likely to begin facing questions from senators starting on Tuesday.
Republicans say nothing has changed, that Roberts is the same well-qualified judge who seemed to be headed for confirmation as an associate justice before Rehnquist died Saturday and the president tapped Roberts for the top spot.
"The fact that he's now been elevated to chief justice shouldn't slow us down at all," said Sen. John Cornyn, R-Texas, a member of the Senate Judiciary Committee that will hold confirmation hearings on the nominee.
Democrats, however, said bumping Roberts up to chief justice instead of having him replace O'Connor means tougher scrutiny of Rehnquist's former Supreme Court clerk.
"Before the Senate acts on John Roberts' new nomination, we should know even more about his record, and we should know whom the president intends to propose to nominate as a replacement for Sandra Day O'Connor," said Sen. Edward M. Kennedy, D-Mass.
No Democrat has yet publicly opposed Roberts' nomination to the Supreme Court, with several actually praising the federal appeals court judge when he was set to be O'Connor's replacement. Assuming no more than a handful of Republicans would fail to vote for Roberts, the only way Democrats might stop Roberts' confirmation would be through a politically bruising filibuster fight, which might weaken them just as President Bush makes a new nomination to replace O'Connor.