A coalition that represents 18,500 Fairfax County employes and public school support personnel announced yesterday it is seeking a 12 percent salary increase and other pay benefits that it said would total about $18 million in next year's county and school budgets.

John Shughrue, chairman of the Employees Advisory Council, said the increase is needed to make county salaries competitive with pay in the private and federal sectors and to narrow the gap between recent salary increases for teachers and the public employes he represents.

The proposed increase would be three times the percentage pay raise that Fairfax police, firefighters, clerical workers and other civil servants received last year, and Shughrue would not estimate its chances of gaining approval. The employes, who are barred by law from striking or bargaining collectively, hope to make their proposed pay package an issue in the county's political campaigns, he said. All nine seats on the Board of Supervisors, which must vote on any pay increase, are up for election on the Nov. 3 ballot.

"We have no real leverage. We are being vocal so that we can be heard by the citizens of Fairfax County," Shughrue said before presenting the council's request at an afternoon news conference.

Reiterating a longstanding complaint, Shughrue and members of the coalition said their salaries have lagged far behind those of teachers under the county's merit pay agreement. The agreement, which will tie teachers' future pay increases to performance, included a 12.1 percent raise last year.

County Executive J. Hamilton Lambert said he had not yet studied the request and would not discuss it in detail, but he disputed Shughrue's estimate of the total cost. "Those numbers have got to be wrong. He's a minimal $10 million low," Lambert said.

Lambert acknowledged that the county has experienced some difficulties competing with other employers for qualified workers, but he disagreed with the argument that all workers should be paid on a par with teachers.

Lambert said the county would respond to the proposed pay package in the coming months.

The coalition also is asking Fairfax officials to revise the pay scale so that workers advance a step each year, and to add a new step for employes who have served more than 15 years. Currently, the nine-step scale spans 13 years.

Shughrue declined to say what action coalition members might take if county officials reject their request, but Bill Hurt, who represents public works employes, said some workers have talked about a slowdown.

Some county employes "would really love to be able to live in the county, but they can't afford it. They like the parks and the schools better here, but there's just no way they can do it with what they're making," Hurt said.