"The decisions of the Supreme Court affect the life of every American," the president said in a televised address from the White House on Tuesday, with federal appeals court Judge John Roberts at his side.

"A nominee to that court must be a person of superb credentials and the highest integrity, a person who will faithfully apply the constitution and keep our founding promise of equal justice under law. I have found such a person in Judge John Roberts," said Bush.

With the choice, Bush shrugged off pressure to pick a woman to replace Justice Sandra Day O'Connor, a moderate conservative who was the first woman to serve on the court and often cast the deciding vote in controversial decisions.

Confirmation

The president urged the divided US Senate, where his Republican party has 55 of 100 seats, to confirm Roberts by the first week of October, when the top US court opens a new session. 

"A nominee to that court must be a person of superb credentials and the highest integrity... I have found such a person in Judge John Roberts"

US President George Bush

"This confirmation can be done in a timely manner," said Bush. "So I have full confidence that the Senate will rise to the occasion and act promptly on this nomination."

The nomination was Bush's first chance to reshape the ideological balance of the court, which has immense influence over the lives of Americans as the final arbiter of the US Constitution and court of last resort.

Because justices serve for life or until they retire - as O'Connor announced she was doing on 1 July - they regularly decide critical and controversial political and legal issues long after the president who picked them has left office.

Paramount decisions

In one of those cases, O'Connor sided with her conservative colleagues in a majority decision to stop vote recounts in Florida in the 2000 election, in effect handing the White House to Bush over Al Gore.

The top Democrat in the Senate, Harry Reid, neither endorsed nor rejected Roberts, but set the stage for tough questioning by saying that the nominee had "suitable legal credentials" but required more scrutiny.

Roberts' last notable decision came only last week when his appeals court overturned a lower court decision that the special military tribunals for suspected terrorists at the Guantanamo detention camp in Cuba were illegal.

The decision was a victory for the Bush administration in its handling of "war on terror" detainees. But a new appeal is now expected to go to the Supreme Court.

Conservative credentials

Roberts graduated from Harvard Law School in 1979, was a clerk to arch-conservative US Supreme Court Chief Justice William Rehnquist, served in president Ronald Reagan's White House, and was a senior federal prosecutor under Bush's father, former president George Bush Sr.

Justice O'Connor announced her
decision to retire on 1 July

The last justice appointed was the liberal Justice Stephen Breyer, who was named by president Bill Clinton and took his seat in August 1994.

Justice Ruth Bader Ginsburg is the sole woman left on the nine-member Supreme Court bench.

Cancer-stricken Chief Justice William Rehnquist had also been seen likely to retire, but he dismissed such talk last week as "speculation and unfounded rumours" and pledged to carry out his duties "as long as my health permits".