Prince George's County Executive Parris Glendening, in a burst of preelection year optimism, said yesterday that the county will continue to fund the magnet school desegregation plan, as well as increase teacher salaries and decrease classroom size beginning next year.

But he stopped short of proposing how the county will pay for all of these enhancements within the confines of a proposed $363.3 million 1986-87 school budget that school board members have already decried as "woefully inadequate."

"It is very clear that we will receive some state assistance" for magnet schools, Glendening said at a news conference held at the county's new drunk driver facility near Upper Marlboro. "Our intention is to fully fund the magnet program but not retreat from funding other educational programs."

Glendening also used the third anniversary of his taking office to outline what he considers to be his administration's successes in transportation, development and human services. He said the county would place a "major, unprecedented" bond referendum on next November's general election ballot that will pay for road improvements in the fast-growing communities of Laurel, Beltsville, Greenbelt and Bowie.

"We need to ensure that the development going on in our communities enhances rather than congests our communities," he said.

In his prepared remarks, Glendening said that the commitment to the $57 million magnet plan "has not dampened our resolve to address our next two education priorities: to increase beginning teachers' salaries and reduce classroom size."

His tone was considerably more upbeat than in past years, when he addressed budget limitations brought about in part because of the county's property tax cap. In his speech, Glendening said he based his optimism for a more flexible budget on the county government's ability to absorb the loss of $11 million in revenue sharing this year and at the same time pay $8.9 million for the first year of the desegregation program.

"It's tight on the budget," Glendening said. "We'll have to watch every penny, but there was no crisis."

County teachers, who enter into contract negotiations with the Prince George's government this week, have long complained of overcrowded classrooms and starting salaries that are the lowest in the Washington metropolitan area. First-year pay for a new teacher with no classroom experience is $15,738. Glendening's education budget proposal includes provisions for a 5 percent annual salary increase for teachers.

"I think you hear him saying what his priorities are, but you don't hear him coming up with the money," said Valerie Preston, executive director of the Prince George's County Educators' Association. "It sounds more like rhetoric than a bold, new plan."

Glendening acknowledged that he has no financing plan in place for his education objectives, saying instead that his staff is "making internal assessments of several options right now" and that it would be premature to talk about those discussions. He also declined to divulge the details of the bond referendum.

State cooperation, he said, will be important if the county is to meet the series of goals he outlined for the final year of his four-year term. His previously strained relations with some members of the county's legislative delegation to Annapolis, he said, have improved, "largely as a result of 1986 being an election year."

Also, his relationship with "an ongoing rational majority" of the County Council, he said, is on "smooth terrain at the moment."