The reverses suffered by the Prince George's County public schools in the last few weeks, which have left it with 1,255 fewer employes and a host of programs cut or eliminated, were but the beginning of harder times to come.

This year's budget was the first sign that the school system and its supporters are losing whatever political clout they may have had. That clout can be expected to further diminish, for two principal reasons.

The first is that, as evidenced by declining enrollment, 70 percent of the county's households have no direct contact with the schools. Traditionally, citizens with children in the system tend to support schools more than those without.

The second reason is that, while 40 percent of county residents are black, more than half the students in public schools are black. These percentages are expected to rise. Increasingly, the part of the population most intimately concerned with what happens with county schools is the portion with the least political power.

It is this politically crippled school system that must face a future in which few dollars will come without a fight. There is no promise that the restrictions of the TRIM charter amendment, which limits property tax revenues to their 1979 level, will be loosened this year. Federal aid to the system is declining. Not only has the growth in state aid slowed, but the results of a pending court case could force further cuts in what the county spends on its students.

With no significant increases in funding, the amount of money spent on county schools is bound to decline as fast as inflation causes costs to increase.

Predictions that black residents will achieve a majority in Prince George's within a few years offer little solace. First, there is no guarantee they will react any differently than whites to the idea of raising taxes to pay for what seem to be limitless requests from the school system. Secondly, because of low voter registration, low turnout and wide dispersal throughout the county, blacks are unlikely to use the force of their numbers to reverse the priorities of the county's taxing and spending policies.

School officials blame the TRIM amendment and its most visible supporter, County Executive Lawrence J. Hogan, for the problems. Superintendent Edward J. Feeney, from the moment he proposed his budget last December, has spoken of its "crippling effect" and called it "the starkest threat to the system's future."

But county residents, who voted overwhelmingly for TRIM in 1978, have given little indication they want it changed this year. Hogan continues to support it. So does TRIM author William Goodman, who is running as a Republican for the county executive's office, which Hogan is leaving to run for the U.S. Senate.

Another candidate, Democrat and County Council member Parris Glendenning, said last year he would stake his political career on the amendment to TRIM. Even if he wins and successfully leads a TRIM modification movement, however, it would be 1984 at the earliest before property tax revenues would start to rise.

The County Council of PTAs has been circulating a "TRIM Plus Four" petition, seeking to have an amendment placed on the ballot. Under TRIM Plus Four, revenue from newly taxable property would be exempt from TRIM's restrictions, and property tax revenue could increase up to 4 percent a year.

Petition organizer William T. Flahive said this week that more than 8,000 of the 10,000 signatures needed to place the proposal on the ballot have been collected. But so far enthusiasm seems lukewarm, and even some of TRIM's most ardent opponents say they are worried that TRIM Plus Four would preclude greater changes they feel will be needed later on.

The County Council issued a unanimous groan at Hogan and TRIM when considering the county budget last month. But its members have done nothing so far to put an anti-TRIM amendment on the ballot, which they have the power to do. This is, after all, an election year and council members are not keen to call for higher taxation.

So, barring an unexpected addition of a revenue source to the county, it is unlikely the county will have more than a few extra pennies for education next year. Each 1 percent rise in inflation means that a $305 million budget is worth $3.05 million less. Enrollment is expected to fall by 4 percent, to 111,300 this September, but school officials say the drop in costs will be less than 4 percent.

The two remaining principal sources of money for education, the state and federal governments, are now less stable than ever. While the federal government has been able to cut education funding less than it had planned, the pinch is still being felt in the counties. Federal money reaching Prince George's next year is expected to fall from $14 million to $12 million, and it is expected to fall further still in future years.

More ominous are the long-term prospects for state aid to education in Prince George's. During the past decade, unrestricted state aid has increased annually, often as much as 10 percent. This year, the increase was only 2.6 percent over last year's aid, bringing the total of state assistance to county schools to about $100 million.

"There really isn't a lot of hope in any of our revenue areas," says George E. Ridler, budget director for the county schools. "The order of the day is austerity, and as you look out farther it's even murkier."

Further complicating the picture--and making prospects still more dismal for Prince George's--is the Somerset v. Hornbeck case. Baltimore Circuit Court Judge David Ross ruled a year ago that the current method of paying for public education, in which some counties spend more of their own money than others, is unconstitutional. Somerset and several of the state's poorer school districts had sued state schools Superintendent David W. Hornbeck, arguing that current financing methods discriminate against poorer counties.

The appeal was heard last month, and the results are expected by September. State education officials expect the ruling to stand and, if it does, the General Assembly will have to figure out how to make spending equal. Because Prince George's spends slightly more than the state average, it only stands to lose.

Whatever happens with this suit, however, every trend suggests that before the decade is over Prince George's will have an underfinanced, predominantly black school system in the process of changing hands. The question is whether the system will slip through the fingers of a new black majority before the hand-off is complete.