WASHINGTON — The Senate Judiciary Committee today approved John Roberts' nomination as the next Supreme Court chief justice, virtually assuring the conservative judge's confirmation by the Senate next week.

Three Democrats joined the committee's 10 majority Republicans in a 13-5 vote to advance the nomination to the full Senate.

Five Democrats — Sens. Dianne Feinstein of California, Joseph Biden of Delaware, Edward Kennedy of Massachusetts, Charles Schumer of New York and Dick Durbin of Illinois — opposed Roberts.

At times, the arguments over whether Roberts is an appropriate successor to the late William H. Rehnquist merged with senators' worries about whom President Bush will choose to be his next nominee to the Court, as the replacement for the retiring Sandra Day O'Connor.

The Senate's 44 Democrats seem to be split on whether they can, or should, mount even symbolic opposition to Roberts. His confirmation as the 109th Supreme Court justice is assured because most of the Senate's 55 Republicans are supporting him and Democrats have decided not to filibuster his nomination.

But Democrats who oppose his nomination said they couldn't take the risk that Roberts would prove a conservative ideologue on the Court.

Feinstein told a packed Judiciary Committee hearing room that her vote was decided after Roberts refused to fully answer questions from her and other Democrats in his confirmation hearing last week.

"I knew as little about what Judge Roberts really thought about issues after the hearings as I did before the hearing. This makes it very hard for me," said Feinstein, an abortion-rights supporter.

"I cannot in good conscience cast a 'yea' vote," she said. "I will cast a 'no' vote."

Biden said his vote was a close call, but Roberts "does not appear to share the same expansive view of fundamental rights of previous nominees I have supported. I'm unwilling to take the constitutional risk at this moment in the court's history."

Sen. Herb Kohl and Russ Feingold, both Wisconsin Democrats, and the committee's top Democrat, Patrick Leahy of Vermont, decided to support making the conservative judge the nation's 17th chief justice.

"I will vote my hopes today and not my fears," Kohl said.

Kohl said Roberts made it clear to him that he would be a modest judge, not an activist, and would approach arguments with an open mind.

"I take him at his word that he will steer the court to serve as an appropriate check on potential abuses of presidential power," Leahy told the committee and former Sen. Fred Thompson, Roberts' escort through the confirmation process, who watched from the crowd.

Those statements likely are directed at the president, who is expected to soon make public his choice to replace O'Connor, who has been a swing voter on many of the Supreme Court's controversial issues.