The Reagan administration is making a new attack on the Supreme Court's landmark Roe vs. Wade decision legalizing abortion, proposing that the justices use a Missouri case to reconsider the 15-year-old ruling.

The proposal came in form of a brief filed with the court Thursday by Solicitor General Charles Fried, who said the Missouri case represents "an appropriate opportunity" for the justices to review the 1973 decision.Pro-choice groups said the timing of the proposal, two days after the general election, was political.

"I guess they were afraid to do this before the election because they thought they might lose the votes of millions of women," said Eve Paul, Planned Parenthood's vice president for legal affairs.

But a Justice Department spokesman, Loye Miller, insisted that the timing was dictated by extended internal discussions at the Justice Department on the question and by extensive staff work that had to be completed.

Fried's brief said the Missouri case "is free of procedural defects and implicates a number of the legislative choices foreclosed by Roe v. Wade."

The solicitor general's brief noted that the Reagan administration's views on abortion were expressed in a case in June 1986, when the government urged that Roe vs. Wade be overturned.

The high court at that time voted 5-4 to reaffirm the earlier ruling, but since then another Reagan appointee has joined the court, Justice Anthony Kennedy. Anti-abortion groups hope that will tilt the court's balance and lead to scuttling of Roe vs. Wade, which held that a woman has a constitutional right to an abortion.

Missouri officials want the Supreme Court to reinstate a strict state anti-abortion law, struck down in July by a federal appeals court which said the statute was invalid under Roe vs. Wade.

The Missouri law declared that human life begins at the moment of conception and said no public funds, employees or facilities could be used to perform or assist in an abortion or to counsel a woman to have an abortion.

A key issue in the Missouri case is whether it is unconstitutional for a state to declare when human life begins. The Missouri law did that, and went on to declare that "unborn children have protectable interests in life, health and well-being."

The 8th U.S. Circuit Court of Appeals in July struck down those declarations, saying that it is unconstitutional for a state to adopt one theory of when human life begins.

Douglas Johnson, legislative director for the National Right to Life Committee, said the Missouri case offers the high court a chance to address important even if it decides not to use the case to overturn Roe vs. Wade.