Since School Superintendent John A. Murphy declared his intention to leave Prince George's County two months ago, his bosses on the school board and community leaders have studiously avoided talking about a successor.

Some still hope to entice Murphy to stay. Others think it is premature to discuss filling his job until he presents them with a departure date. And others say they have been too absorbed with the school system's mounting financial problems to broach such a potentially divisive topic.

But Murphy's extended public search for a new job is prompting some elected officials to try to force the issue.

Last week, in an attempt to promote a dialogue about life after Murphy, the Prince George's County Alliance of Black Elected Officials sent school board members a letter urging them to "act quickly" in establishing a search process and identifying the qualities they want a new superintendent to possess.

"The Alliance is of the opinion that it is important for the school board to act now to clearly define the way in which a new superintendent will be chosen if and when Dr. Murphy leaves," State's Attorney Alex Williams, the group's chairman, wrote in the letter.

Williams added that his organization is "particularly concerned that leaders of the minority community be fully involved in the decision-making process" because the county's student population is more than 65 percent black.

Last February, the school board's effort to circumvent an earlier job search by Murphy angered some black leaders in Prince George's, who complained that the board's decision to offer the superintendent a 10-year, $150,000-a-year contract had been made without their input. Some thought the extended contract would impede efforts to hire a black superintendent.

School board Chairman Catherine M. Burch (District 3) said she intends to call a meeting this month to discuss Murphy's plans to leave.

Two board members said the board may explore offering Murphy an inducement to remain in Prince George's, an outcome they believe most county residents support. During his six years in Prince George's, the superintendent has been widely credited with raising student test scores and improving the image of county's beleaguered school system.

"If the board provided him some type of incentive, I think he would consider staying," said board member Suzanne M. Plogman (District 2). She said she is unsure what kind of incentives could be offered.

Board member Marcy C. Canavan (District 9) said she intends to ask her colleagues to sign statements pledging their commitment to renew Murphy's contract for four more years when it expires in June 1992.

Although the school board's desire to prevent Murphy's departure last year sparked a community uproar that eventually strengthened his commitment to leave, Canavan said she does not think her idea would meet with a similar reaction this time around.

"For the board to do nothing is a mistake," Canavan said. "We have to think about what is best for our children, not a vocal minority that wants to play politics."

Murphy, meanwhile, said Wednesday that he is not an active candidate for any other school posts. But he said he still is "receptive to exploring other opportunities."

"The idea of leaving Prince George's is not a positive one for me," he said. "However, I do feel there have been some very blatant directives to me that indicate I should be leaving . . . . Do I expect to be here in the future? No."

Murphy said that although he hopes to have his career plans resolved "as quickly as I can," he could not offer a timetable for his departure because he wants "to be very selective about where I go."

Ira W. Krinsky, a Los Angeles-based consultant who conducts searches for educational administrators, said it is too early to identify possible replacements for Murphy elsewhere in the country because the school board has not decided what kind of candidate it wants.

The names of several local officials have surfaced as possible candidates. They include Deputy Superintendent Edward Felagy; Jerome Clark, associate superintendent for personnel; Art Curry, principal of Forestville High School; Warren Simmons, director of instructional support programs; and area Assistant Superintendents Joseph Harriston and Jesse Freeman.