WASHINGTON — Hours after the Senate confirmed him overwhelmingly, John G. Roberts Jr. took the oath Thursday as the 17th chief justice of the United States.
Now, President Bush must nominate someone to succeed retiring Justice Sandra Day O'Connor, a selection likely to determine the direction of the Roberts-led Supreme Court. On Monday, the court begins a new term.
The 78-22 confirmation vote for Roberts, the first new appointee to the court in more than a decade, was a triumph for Bush.
Roberts succeeds the judge for whom he once clerked, Chief Justice William H. Rehnquist, who died Sept. 3. At age 50, Roberts is the youngest chief justice since 45-year-old John Marshall was confirmed in 1801. Justices have lifetime tenure, so Roberts might for decades influence decisions not only on such issues as abortion rights and gay rights but on matters sure to grow in importance, such as the reach of technology into the private lives of Americans.
Bush's choice of Roberts -- who combined stellar legal credentials with a modest manner -- divided and disarmed Democrats. Roberts' conservative legal record pleased Republicans, and his pledge during confirmation hearings to respect legal precedent over ideology helped him win significant Democratic support.
Half of the Senate's 44 Democrats joined all 55 Republicans and the chamber's independent, James M. Jeffords of Vermont, to confirm Roberts.
The swearing-in at the White House was a respite for Bush from weeks of criticism of federal response to Hurricane Katrina. Bush praised Roberts, whom he appointed two years ago to be a federal appellate court judge, as "a man with an astute mind and a kind heart."
Surrounded by justices, congressional leaders and his family, Roberts offered the simple promise "to do the best job I possibly can do. And I will try to do that every day."
He also noted his bipartisan backing: "I view the vote this morning as confirmation of what is, for me, a bedrock principle -- that judging is different from politics. And I appreciate the vote very much."
Even as Roberts was confirmed, much of Washington's attention had shifted to whom Bush will choose to succeed O'Connor, who in July announced plans to retire.
Roberts was initially tapped by Bush to succeed O'Connor. The president chose Roberts to be chief justice after the death of Rehnquist, a staunch conservative who had served on the court since 1972 and led it since 1986.
Roberts is unlikely to dramatically alter the court's political balance, another reason his confirmation went smoothly for the White House. But O'Connor -- poised between the court's liberal and conservative wings -- had been a swing vote in recent years on several issues, so the choice of her successor is expected to be more contentious.
White House aides have acknowledged that it would not be easy for the next nominee to win such bipartisan support.
Democrats have reminded Republicans that they were willing to filibuster a nominee they consider unsuitable.
"If it's an ideologue ... there would be a good chance we would move to block the vote on the floor," Sen. Charles E. Schumer (D-N.Y.) said Thursday. "The message to the president is we would eagerly embrace a consensus nominee, a nominee who would be mainstream, who ... would not turn the clock back on basic rights."
Sen. Dianne Feinstein (D-Calif.) said: "In the last 10 years, the court has moved dramatically to the right.... I think the president is well advised to take heed of this. The nation is extraordinarily divided and polarized."
Feinstein voted against Roberts' confirmation, as did California's other senator, Barbara Boxer.
Republicans were bracing for a harsher fight over the next nominee, making a point of praising Democrats' civility during Roberts' confirmation process.
"As we move forward to fill the second vacancy on the high court, I urge my colleagues to be mindful of the lessons that we've learned from Chief Justice Roberts' nomination," Senate Majority Leader Bill Frist (R-Tenn.) said Thursday. "By focusing on qualifications and judicial philosophy rather than political ideology, we can continue to preserve the integrity of the judicial nominations process."
The president commented this week that he was "mindful that diversity is one of the strengths of this country," which led many to speculate he would choose a woman or a minority to succeed O'Connor.
Names that have been mentioned include Bush's attorney general, Alberto R. Gonzales, or his White House counsel, Harriet Miers, either of whom might avoid an all-out battle with Senate Democrats. Gonzales, if confirmed, would be the court's first Latino member; Miers would keep the court's number of women at two.
However, some conservative antiabortion groups have said they would be disappointed with such nominations, and they might actively oppose Gonzales, whom they consider less of an abortion opponent than they would like.