The American Bar Association, the nation's main organization of lawyers, yesterday issued its highest ranking to Supreme Court nominee John G. Roberts Jr., concluding that he is "well-qualified" to succeed outgoing Justice Sandra Day O'Connor.

The ABA notified the White House, the Justice Department and members of the Senate Judiciary Committee, saying that it believes Roberts has the temperament, integrity and professional competence to sit on the nation's highest court, according to Thomas Z. Hayward Jr., chairman of the association's Standing Committee on Federal Judiciary, a 15-member panel of lawyers who vetted the nominee.

The glowing review of the judge President Bush has chosen to fill his first Supreme Court vacancy comes amid a major dispute between the White House and the ABA that began two months after the president took office. In March 2001, Bush substantially downgraded the organization's role in vetting judicial candidates, discontinuing a tradition dating to the 1950s in which the ABA, which represents more than 400,000 lawyers, had given the White House its assessment of potential judicial candidates before the president chose his nominees.

Bush said at the time that it was unfair to allow "any single group such a preferential, quasi-official role." His move delighted many Republicans who had argued for the previous few decades that the organization had a liberal tilt.

Roberts, a lawyer and judge since 2003 on the U.S. Court of Appeals for the District of Columbia Circuit, is the first Supreme Court nominee since the president limited the group's influence. Hayward said the ABA treated his candidacy the same way it has the more than 200 other judicial candidates Bush has selected since then: The judge-rating committee evaluated his nomination after the fact.

Yesterday, it was Democrats who sought to play down the significance of the group's work.

Sen. Patrick J. Leahy (Vt.), the Senate Judiciary Committee's ranking Democrat, thanked the group for its "effort and input" but said its vetting process had "limitations," pointing out that the review was completed before the release of documents that are emerging now about Roberts's work and views during part of the 1980s, when he worked in the Reagan White House and Justice Department.

Democratic senators and liberal advocacy groups emphasized that the ABA had not attempted to evaluate Roberts's judicial philosophy, which they said is a significant factor in whether he deserves to be confirmed.

The White House, congressional Republicans and their conservative allies were silent about the ABA's rating.

The ABA issued the results of its review as leaders of the Senate Judiciary Committee announced details of their plans for Roberts's confirmation hearings, to start on Sept. 6. Leahy and Judiciary Committee Chairman Arlen Specter (R-Pa.) issued a joint letter to panel members saying that each senator will be allotted 50 minutes of questioning of Roberts in two rounds, with additional rounds to be scheduled if necessary. They also said that one of the committee's sessions will be private.

Hayward said that the ABA has been invited to every Supreme Court confirmation since the group began its rating. But asked whether he will be invited this time, Hayward replied: "I have no idea."

Roberts is the first high court candidate since the 1950s not vetted by the ABA before nomination.