President Bush has nominated conservative federal appeals court Judge John Roberts to the U.S. Supreme Court, to replace the retiring Justice Sandra Day O'Connor.

Mr. Bush made the formal announcement in a televised address at the White House Tuesday night. Judge Roberts stood next to the president as he announced his choice.

President Bush called Judge Roberts a person of superb credentials and high integrity.

Mr. Bush called on the Senate to begin what he called a "dignified and timely" confirmation process, saying he hopes Judge Roberts will be confirmed before the Supreme Court returns from its recess in October.

The Roberts nomination is expected to spark a political battle between Republicans and Democrats, and set off a flurry of activity by private groups seeking to influence the Senate's decision.

It is the first vacancy on the nation's top court in 11 years.

The 50-year-old Judge Roberts will be President Bush's first nominee for the Supreme Court.  His selection is expected to trigger a politically charged battle over the direction of the nation's highest court.

As an attorney and associate counsel to former President Ronald Reagan, John Roberts argued several cases before the Supreme Court.  His nomination to the high court must be approved by the U.S. Senate. 

This undated photo provided by the U.S. Court of Appeals for the District of Columbia Circuit shows Judge John G. Roberts, Jr.
In the 1980's, he worked as a clerk for William Rehnquist, who is now chief justice but then was an associate justice on the high court.

As a private attorney and later a deputy solicitor general under former President George H.W. Bush, John Roberts presented oral arguments in more than 30 cases before the Supreme Court. He also was an associate counsel to President Ronald Reagan.

He currently serves as an appeals court judge in the Washington, D.C., circuit, following his 2003 nomination by the current President Bush.

Mr. Bush's father nominated Judge Roberts to the federal appeals court during his administration, but the Senate did not confirm that nomination.

John Roberts graduated with honors from Harvard Law School.

Some information for this report provided by AFP, AP.