A $5.6 million plan to extend the Fairfax County elementary school day on Mondays has met with a resounding chorus of catcalls from parents, teachers and politicians alike.

In the four days since Superintendent Robert R. Spillane unveiled a proposal to eliminate the 20-year-old practice of closing elementary schools as much as 2 1/2 hours early on Mondays, virtually no one outside the School Board has spoken out in support of the idea.

Critics complain that the schedule change is a luxury in a time of fiscal belt-tightening.

"The bottom line is whatever we do, if we proceed, is going to cost money and we don't have it," Supervisor Sharon Bulova (D-Annandale), chairman of the board's budget subcommittee, said yesterday. "The money's going to have to come from somewhere, and I would hate to have it come from textbooks or other educational" items.

Parents, many of whom might have supported the idea in any other year, say they fear the plan would drain money away from other popular programs.

"The biggest question is: Why now?" said Jane Strauss, president of the County Council of PTAs. "There is no groundswell to do this from either a social day-care need or an educational need. The attitude {among parents} is, 'You're going to have to come explain it to us why we want to do this.' "

Under Spillane's plan, the school district would hire 129 new teachers to relieve homeroom teachers of their art and physical education instruction duties, thus giving them planning time to make up for what they would lose from Monday afternoons. Teachers now use the time after school closes on Mondays to meet with colleagues and plan lessons.

Only two other Washington area districts, Prince William and Arlington counties, close elementary schools early one day each week.

Kohann H. Whitney (Centreville), chairman of the School Board, has been the main champion of extending the Monday school day, arguing that the elimination of early closings would add 2 1/2 hours of classroom time for students each week. Last year, she persuaded the board to unanimously approve the change in concept. Spillane's latest plan, she said, is "real solid" and still feasible even in the face of tightening revenue.

"If you believe that youngsters being exposed to more core education is valuable, then the $5.6 million isn't all that much," agreed board member Anthony Cardinale (Springfield). "You can't keep postponing something like this."

But teachers complain that while Spillane's proposal would give them planning time, it would be difficult to collaborate with colleagues, something they say they do on Mondays.

And yesterday, the Board of Supervisors derided the School Board for even thinking of launching a costly initiative at a time of dismal fiscal forecasts, hiring freezes and budget limitations.

"I don't think this is the time to be embarking on any new program of that magnitude, particularly when no public support has been demonstrated for it," said Supervisor Thomas M. Davis III (R-Mason).

Even on the School Board, support for the plan has plummetted in the last few months as the economy has taken a nose dive.

Based on public statements and interviews, the 10-member board appears evenly split on the issue, which will be up for a vote Nov. 15.

Along with Whitney and Cardinale, Vice Chairman Laura I. McDowall (Annandale) and member Armando M. Rodriguez (Mount Vernon) strongly support it. Board members Carla M. Yock (Mason), Letty A. Fleetwood (Providence), Anthony T. Lane (Lee) and Joanne T. Field (Dranesville) all oppose it or seem to be leaning in that direction.

Board member Robert E. Frye (At Large) said he is holding out hope the county somehow can afford it, while the 10th member, Nathaniel Choate (At Large), could not be reached for comment.

Meanwhile, the two teachers unions are marshaling their telephone banks and letter-writers in an effort to swing the crucial fifth vote. The larger of the two unions, the Fairfax Education Association, today will begin lobbying supervisors to pressure the School Board members they appoint to vote no.

"If they're looking for our support next fall when they're running their campaigns, they better at least sound like they're pro-education," said union President Maureen Daniels.