Fairfax County school officials yesterday launched what they said will be an aggressive campaign to sell the need for a $74.8 million school bond referendum this fall.

The school bond referendum, the largest in the county's history, will be on the Nov. 6 ballot, and some officials expressed concern that many Fairfax voters will be more knowledgeable about national issues than local education needs.

"The major problem will be that you'll have one of the biggest voter turnouts because of the presidential election, and if they go to the polls and don't know anything about the school bond, they'll have a tendency to vote no," said Suzanne H. Paciulli at a press conference.

Paciulli, former president of the Fairfax County Chamber of Commerce and chairman of the Virginia State Board of Commerce, has been chosen to head the school bond campaign. The $15,000 cost will be funded by private donations, she said.

Superintendent William J. Burkholder said yesterday he doubts the members of the Fairfax League of Women Voters and the Fairfax Federation of Citizen Associations, two influential community organizations whose leaders have criticized the bonds, will share those views. He described initial opposition to the referendum as the disappointment of citizens whose individual schools did not secure funding.

Responding to charges that the bond proposal contradicts a longstanding policy against piecemeal improvements, the superintendent said Fairfax could not afford complete renovations at all 65 schools in the county built before 1970.

"We chose to spread money among as many schools as we possibly could," he said, including adding gymnasiums and music rooms at 13 elementary schools.

He also said the elementary schools that won't receive improvements are not secretly targeted for closure as some critics have alleged.

The bonds would provide funds for building new schools in the growing western part of the county and improving older schools in the stable eastern part of the county.

Although the school projects have been well supported by Fairfax voters in the past, the fall referendum did not muster unanimous backing from the County School Board and had lukewarm support from the Board of Supervisors. The factors have prompted concerns that the referendum could face serious opposition.