Judge John Roberts is sworn in by Justice John Paul Stevens, as 17th chief justice of the United States in East Room of White House

The new Chief Justice of the United States, John Roberts, will preside over the opening of the next Supreme Court term beginning Monday.

Chief Justice Roberts, 50, could have a significant impact on the high court for decades to come.

He replaces the late Chief Justice William Rehnquist, who died of thyroid cancer in early September after leading the Supreme Court for the past 19 years.

"I will try to ensure, in the discharge of my responsibilities that, with the help of my colleagues, I can pass on to my children's generation a charter of self-government as strong and as vibrant as the one that Chief Justice Rehnquist passed on to us," said Justice Roberts.

Chief Justice Roberts easily won confirmation in the Senate where all the Republicans and half of opposition Democrats supported him.

President Bush says the bipartisan show of support was a tribute to his character and legal qualifications.

John Roberts, left, and President Bush

"As Judge Roberts prepares to lead the judicial branch of government, all Americans can be confident that the 17th Chief Justice of the United States will be prudent in exercising judicial power, firm in defending judicial independence, and above all, a faithful guardian of the Constitution," said Mr. Bush.

The chief justice has the responsibility of presiding over the Supreme Court and the judicial branch of the federal government.  While the chief justice has only one vote in deciding cases like the other eight justices on the high court, he or she does have the ability to choose which justice will write the majority opinion in a given case provided the chief is in the majority.

Douglas Kmiec is a constitutional law expert at Pepperdine University Law School in California.

"One would expect that John Roberts will be very effective in the role of the center seat," he said.  "He is a warm and genial personality.  He is someone who has described his judicial philosophy as being guided by the virtue of humility."

With Chief Justice Roberts confirmed on the court, President Bush must now nominate a successor for retiring Justice Sandra Day O'Connor.

Legal and political analysts say the confirmation battle over her replacement will likely be more intense than the Senate debate over John Roberts.

A.E. Dick Howard is a legal expert at the University of Virginia.  He spoke to VOA's Focus program.

"The more critical seat from the standpoint of the court's lineup is Justice O'Connor's seat," said Mr. Howard.  "She was a conservative, but a more moderate conservative.  She was often the critical vote in five to four cases.  She had a role of pulling the court somewhat to the center."

Opposition Democrats are warning the president not to appoint an ardent conservative to replace Justice O'Connor.

Senator Charles Schumer is a Democrat from New York and a member of the Senate Judiciary Committee, the panel that will hold confirmation hearings on President Bush's Supreme Court nominee.

"If ever there was a time for consensus, the time is now," said Mr. Schumer.

As its next term gets under way, the Supreme Court is scheduled to hear cases on several contentious legal issues.  These include the constitutionality of campaign finance laws, new restrictions on abortion rights and a dispute over physician-assisted suicide for the terminally ill in Oregon.