The National Organization for Women yesterday became the first major organization to oppose Supreme Court nominee Anthony M. Kennedy, departing from the hesitant approach of other groups that led the drive against Robert H. Bork, and branded Kennedy a "sexist" unqualified to sit on the high court.

NOW President Molly Yard told a news conference that Kennedy, a federal appeals court judge in Sacramento, "would be a disaster for women" if confirmed as a justice. She cited a decision by Kennedy in which he rejected a requirement that women be paid based on the "comparable worth" of their jobs and another in which he found that the Navy could constitutionally fire homosexual sailors, as well as Kennedy's membership in an all-male San Francisco private club. Kennedy resigned his 25-year membership in the club last month.

Kennedy, who paid a series of courtesy calls at Senate offices yesterday, said he would "be glad to respond to that {the NOW charges} at the Senate Judiciary Committee hearing."

When that will be is uncertain. Committee Democrats proposed to the White House yesterday that the confirmation hearings begin December 14, but that the committee hold off voting on the nomination until shortly after Congress returns from its winter recess, which is expected to end Jan. 19, according to committee member Sen. Howard M. Metzenbaum (D-Ohio). Alternative dates are Jan. 5 and Jan. 20.

Committee Chairman Joseph R. Biden Jr. (D-Del.), ranking Republican Sen. Strom Thurmond (S.C.) and White House chief of staff Howard H. Baker Jr. met to discuss the timetable. A final decision is expected today.

Biden predicted the hearings would take only three to five days, compared to the 12 days of hearings on Bork, who was defeated by the Senate 58 to 42. "I think this is going to go real quickly, although, sure, there will be opposition," Biden said.

Committee staff members have said the hearings could not begin until after the FBI has completed its background check of Kennedy and the American Bar Association finishes its evaluation. A committee source said the committee expects to have the FBI report today and the ABA evaluation after Thanksgiving.

While NOW was coming out against Kennedy, representatives of about 100 organizations in the broad coalition of civil rights, civil liberties, labor, and women's groups that led the anti-Bork battle met for the first time since Kennedy was nominated Nov. 11 to discuss research into Kennedy's judicial opinions and background.

Members of the groups expressed concern that the December starting date would not give them adequate time to scrutinize Kennedy's record and take a position on the nomination.

Ralph G. Neas, executive director of the Leadership Conference on Civil Rights, said the coalition -- which signaled its opposition to Bork even before he was nominated -- is not yet ready to take a stand on Kennedy, who is far less well known than Bork and has a 12-year-record of opinions on the 9th U.S. Circuit Court of Appeals.

Neas said that the conference "at this time does not have a position on the Kennedy nomination." He noted, however, that several Kennedy opinions on voting rights, school desegregation, housing discrimination, and sex discrimination "have raised some problems and we're taking a look at them."

Yard said she hoped the other groups would join NOW in opposing Kennedy. "We did read enough of his opinions to know that he was not a supporter of our concerns . . .," Yard said.

In the comparable-worth ruling, Kennedy in 1985 overturned a lower court decision that required Washington state to implement a system that would provide equal pay for different jobs of similar value. Kennedy said federal laws prohibiting sex discrimination did not cover disparities in pay between jobs held primarily by women and those dominated by men, without other proof of discrimination.

Yard said Kennedy's decision in 1980 upholding the Navy's firing of homosexuals raises questions about his application of the constitutional right to privacy that has been the basis for the high court's abortion rulings. "What will he say on the right of privacy of women to control their reproductive rights?" she asked.