R. David Hall says he will step down as D.C. school board president, and several board members say Linda Cropp, the board member from Ward 4 and wife of a top aide to Mayor Marion Barry, has quietly lined up the votes to succeed him.

Cropp appears to have enough support among board members to defeat Nate Bush (Ward 7), the other candidate for the post being vacated this month by Hall (Ward 2). Cropp and Bush were easily reelected last month.

Hall said in an interview that he will not seek a fourth term as leader of the 11-member board. The president, who is paid $26,000 a year, $2,000 more than board members, runs board meetings, appoints committees and shapes the agenda. Board members consider the job, the most public of board positions, a steppingstone to citywide elective office.

"It's been three years and I've finished this portion of my career," Hall said. "In some ways, it's easier not being president to get things done."

Hall would not discuss his rumored interest in running for mayor, but confirmed that "there are other citywide positions I would be interested in." Hall said he is "not ruling out" running for citywide office before his school board term expires in 1990.

Between now and 1990, Hall could run for mayor, D.C. Council chairman or one of the council at-large seats.

Bush and Cropp have been campaigning quietly all fall for the presidency.

Cropp is married to Dwight Cropp, the city's director of intergovernmental relations and one of Barry's closest aides. Board members who asked not to be identified said they hope Linda Cropp's tie to the mayor will help the school system in its budget battles with the city.

"Cropp is relatively knowledgeable, although she does have a tendency to overstate the system's achievements," said a parent activist who believes Cropp would do well as president.

Cropp, who has worked closely with Hall especially in the last year, is expected to draw support from the majority that Hall built, including Wanda Washburn (Ward 3), Wilma Harvey (Ward 1), and Phyllis Young (At Large), who worked on Cropp's campaign.

Members Bob Boyd (Ward 6) and David Eaton (At Large), who vote with Hall less frequently, and newly elected member Angie Corley (Ward 5) also are said to be leaning toward Cropp.

Bush, chairman of the board's Finance Committee, is likely to win support from R. Calvin Lockridge (Ward 8) and Eugene Kinlow (At Large).

Hall has not publicly made an endorsement.

Bush, whose campaign has been more open than Cropp's, said, "I think I can win the support I need." As president, he would emphasize long-range planning and increased oversight of school administrators.

He also wants to reduce peer pressure against achievement in schools, by, for example, using uniforms to reduce pressure to buy high-priced fashions.

Cropp confirmed she is campaigning for the post, but declined to discuss her chances or what she might do as president.

"We'll find out the result when the members vote," she said.

The vote, like most board votes, is likely to be unanimous, Hall said. Hall has made public unanimity a trademark of his tenure as president.

Hall, who also acts as spokesman for the board, has had such success in keeping board disagreements out of the public eye that meetings have become quiet, almost sleepy affairs.

The new president will choose the chairman of the committee searching for a successor to Superintendent Floretta D. McKenzie, who is leaving this winter to form a consulting firm. Hall, the current chairman, said he wants to continue.