The Cambridge School Committee last night postponed a final decision on how to desegregate the city's public schools, amid signs that a consensus is forming in favor of a proposal more moderate than the one recommended by School Superintendent William Lannon.

A lawyer's opinion on the city's legal obligation to desegregate is due later this week, but many board members now appear unwilling to vote for the section of Lannon's proposal creating "educational zones" from which new students could be randomly assigned to different schools.

Committee members appear more likely to support the redistricting portion of Lannon's plan, which would redraw school district lines in an attempt to mix white and minority students more evenly in the Cambridge elementary schools.

"Personally, I think holding off on the educational zones plan might make a lot of sense," Alice Wolf, vice chairman of the school committee, said yesterday. Wolf added, however, that she had not polled committee members on their opinions.

"I just don't think we have the data now to do something on that immense a scale," Wolf said, adding that she believed the zones plan had not been "drawn up in a very orderly fashion."

Emphasizing that it is "too early to make any predictions," committee member Glenn Koocher '71 said last night that deferring the educational zones portion of the plan was "among the things to be very, very seriously considered."

Under Lannon's proposal, the city is redistricted and then divided into three "educational zones." Students entering the system can be randomly assigned from one school in the zone to another, depending on the need for racial balance.

The proposal hit its first obstacle a week ago, when John Akula, a local lawyer, submitted a brief to the committee arguing that under state law Cambridge was under no obligation to "eliminate racially imbalanced or isolated schools."

Akula told the committee he would favor the immediate adoption of the redistricting plan and the deferment of the zones proposal until the city's legal duties could be "clearly defined."

Lannon and other school department officials have argued that redistricting alone would solve racial balance problems only temporarily and that population shifts would soon unbalance the system again unless the zone plan was in a place to allow random assignments of new students.

The state school board, in a letter sent to the committee last week, acknowledged that it could not force the city to racially balance its school but added that it could stop state funding for the system if it determined sufficient progress toward desegregation had not been accomplished.