WASHINGTON -- Senate Judiciary Chairman Arlen Specter said yesterday he would vote to confirm John G. Roberts Jr. as chief justice of the United States, stating Roberts' "extraordinary academic record" and "illustrious career" had made him well qualified to lead the Supreme Court.

In a speech on the Senate floor, the Pennsylvania Republican said he was reassured by Roberts' statements that the Constitution was a document "intended to apply in a meaningful way down through the ages" -- which he considered a departure from judges who have argued that the Constitution should be interpreted as it was originally written.

Specter, an abortion rights supporter, said Roberts had strongly affirmed his belief in the right to privacy, which laid the groundwork for the 1972 Roe v. Wade decision legalizing abortion, and in the importance of judicial precedent, making it less likely that he'd try to overturn Roe.

Most, if not all, of the Senate's 55 Republicans are expected to vote for Roberts, but Specter was among the first to formally announce his position.

A fellow moderate Republican who also supports abortion rights, Susan Collins of Maine, said this weekend she intended to support Roberts.

Sean Rushton, executive director of the conservative Committee for Justice, said the two announcements were likely to help smooth the way for Roberts when the full Senate considers the nomination during the week of Sept. 26.

"It makes it harder for conservative and moderate Democrats to vote against Roberts," Rushton said. "I think it sets the tone that there is substantial moderate support for the nominee."

So far, no Democrat has publicly announced opposition to Roberts. Senate Minority Leader Harry Reid, D-Nev., asked Democrats to hold off announcing how they would vote until after their party meets during the Senate's weekly policy luncheon today. Reid said last week that he would not ask his party to vote in a bloc and that each senator should vote his or her conscience.

Specter's decision was not surprising, said Elliot Mincberg, general counsel and legal director of the liberal group People for the American Way.

"Although [Specter] did ask some good questions in the hearing room -- he made it quite clear after Roberts refused to answer them that that was OK with him, and that was extremely disappointing," said Mincberg, who said he thought Specter was under pressure to support Roberts from conservative groups who fought Specter's elevation to the chairmanship last fall.

In his speech, Specter undercut the argument of many of the committee's Democrats that they did not have enough information about Roberts to make a decision.

With more than 70,000 pages of documents from Roberts' career, his legal briefs and his opinions in the cases he has decided as a judge on the U.S. Court of Appeals for the D.C. Circuit, Specter said yesterday he thought the full Senate had an "ample basis to evaluate Judge Roberts' qualifications."

In expanded remarks submitted for the Congressional Record, Specter said he was convinced that Roberts' answers during the hearing demonstrated that he would "take a fair, non-ideological approach to the law" and that he condemned "judicial activism of all stripes, from the left and right."

Alluding to the concerns of Democrats about memos Roberts wrote when he was a young aide in the Reagan administration, Specter said that although Roberts did not disavow some his views from that period, his overall impression was that Roberts "has grown considerably in the intervening 20 years."

President Bush will meet with Specter, the Senate's minority and majority leader and the Senate Judiciary Committee's ranking Democrat tomorrow at the White House to discuss the second nomination.

The Senate Judiciary Committee's eight Democrats and 10 Republicans will vote on Roberts' nomination Thursday; the full Senate -- 55 Republicans, 44 Democrats and one independent -- is expected to take up the matter next week.