Senate Democrats signaled yesterday that they plan to question Supreme Court nominee John G. Roberts Jr. vigorously on what they see as discrepancies between recent statements and his writings as an up-and-coming lawyer in the Reagan and first Bush administrations.

In particular Democrats said that at next month's confirmation hearings they plan to focus on Roberts's stated views on the issue of how much justices should be influenced by rulings of the high court. That is a critical question for those who want to know whether he would vote to overturn decisions such as Roe v. Wade, the landmark 1973 case that established a constitutional right to abortion.

Responding to a Senate questionnaire, Roberts said he would respect previous Supreme Court rulings. "Precedent," he wrote in a 67-page statement released this week, "plays an important role in promoting the stability of the legal system, and a sound judicial philosophy should reflect recognition of the fact that the judge operates within a system of rules developed over the years by other judges equally striving to live up to the judicial oath."

Democrats said Roberts needs to reconcile that statement with memos he wrote in the 1980s and early 1990s questioning court precedent when he was a special assistant to Attorney General William French Smith in the Reagan administration, as well as with actions he took as a principal deputy solicitor general under President George H.W. Bush.

"There are a lot of questions that have to be asked," Helaine Greenfeld, the senior nominations counsel to the Democratic senators, told reporters in a conference call. "The senators will want to know how his view of precedent now squares with his view of precedent then."

The conference call was organized by staffers of Sen. Patrick J. Leahy of Vermont, the ranking Democrat on the Senate Judiciary Committee.

In one 1981 memo, for instance, Roberts questioned the legal reasoning used by the Supreme Court in its finding that anti-discrimination laws did not prohibit all race-conscious affirmative-action plans. Just two years after the decision, Roberts noted that because of a change in the court's makeup, it now "has only four supporters," intimating that it could be struck down by a new majority. He added: "We do not accept it as the guiding principle in this area."

In another 1981 memo, Roberts discussed a Supreme Court decision that struck down state laws imposing a one-year residency requirement for welfare benefits, criticizing the court's finding that there was, as he put it, a "so-called 'fundamental right to travel.' "

In a third memo that year, Roberts called the legal concept that underpins the right to an abortion the "so-called 'right to privacy.' " In the memo, Roberts praised a lecture given by a former solicitor general, who, as Roberts put it, argues "as we have, that such an amorphous right is not to be found in the Constitution."

During Roberts's 1989-1993 tenure in the solicitor general's office, he also co-wrote a brief that argued that Roe v. Wade was wrongly decided and should be overturned.

During his confirmation hearings two years ago for his current seat on the U.S. Court of Appeals, Roberts said that "nothing about what my personal views were or are should be inferred from the fact that my name appears on the federal government's brief."

To date, the Bush administration has resisted requests by Senate Democrats to turn over documents from that period that could help clarify his personal views on the matter, saying they should be kept confidential to ensure that administrations receive candid legal advice.

Sean Rushton, executive director of the conservative Committee for Justice, said the Democratic strategy is predictable. "They want him to all but commit to vote in certain ways, and when he won't answer those questions, they'll claim he's not being forthcoming and that they have no choice but to vote against him."