For many of Prince George's County's black political and community leaders, getting the County Council to set aside 30 percent of county government business exclusively for minority contractors was a key test of political strength.

Having failed that last week, when the council voted 5 to 2 to reject the proposal, black activists have threatened political reprisals against county officials in the 1990 elections and legal action to challenge county procurement practices on the basis that they discriminate against minorities.

How far they will get remains unclear, and many of the most outspoken proponents of the set-aside law are divided on the best way to respond to the defeat of what was seen as the primary black political agenda item in a county where minorities make up more than 45 percent of the population.

Yet, political observers said, there is no doubt that the vote has created hard feelings, especially toward Council Chairman Hilda R. Pemberton and County Executive Parris Glendening, who worked to block the set-aside legislation and instead shore up the county's voluntary minority business program.

Proponents of the change assert that the voluntary program has failed to assure black businesses a fair share of county government business and argue that 30 percent must be reserved by law for minorities. County officials, however, maintain that such a set-aside would be illegal under the county charter, which requires competitive bidding in most instances.

"The general feeling is we are keeping a report card and we will let the people know what the elected officials did {on this issue} when they were in office," said Cora Rice, a member of the Coalition for Black Economic Development, which pushed for the set-aside bill. "We are going to work hard to get these people out."

But observers doubt that the unhappiness will translate into any long-term political problems for County Council members; for Pemberton, who is black and who has offered to let voters decide the set-aside issue, or for Glendening, who has aligned himself closely with the black community.

"In terms of the coalition and the people who invested a lot of time and energy in {the legislation}, there are hard feelings," said state Sen. Albert R. Wynn (D-Prince George's), who supported the set-aside bill. "Some of them said they will continue to pursue the issue. But . . . what is accomplished with Hilda's and Parris' bill will determine how this thing is played out in 1990."

Lance W. Billingsley, a close Glendening adviser, observed: "If the county makes good-faith, bottom-line efforts to institute an affirmative action program, it is not going to be an issue at all. If the county does not deliver on its program, it is going to create a problem."

Since the spring, leaders of the most active civil rights and black business groups have been deadlocked with county officials over the best way to boost the proportion of contracts that go to minority firms.

Since 1984, the county has fallen short of its stated goal of awarding 30 percent of the total value of its contracts to minority companies. In the fiscal year that ended in June, the county awarded 18 percent of contracts to minority companies. Figures for the first quarter of this fiscal year are to be released today, a county official said, but indications are that the awards have not increased substantially and do not approach 30 percent.

The Coalition for Black Economic Development -- which includes the county chapter of the NAACP, the National Business League of Southern Maryland and the Southern Christian Leadership Conference -- and many black elected officials have emphasized what they call the ineffectiveness of the county's voluntary program. They advocate a set-aside program, similar to the one now used in the District.

The question of what is permissible under the county charter is expected to fuel a continuing debate on the issue. Tomorrow, the council is expected to adopt what is seen as a compromise bill. It would authorize a referendum to take out charter language that many county officials believe prohibits a set-aside program.

Set-aside proponents say that a charter amendment is not necessary and are concerned that the voters might turn it down. Instead, coalition members said, they will gather information to attempt to show that the county's contracting practices discriminate against minorities, and thus that a set-aside is a necessary remedy even under the existing charter.

"The charter amendment is risky. It will be divisive and will be polarizing because it will be simplified as giving something to blacks," Wynn said. "There are 15 exceptions in the current charter {awarding contracts} to the lowest competitive bid. There has not been work to see if a set-aside would fit under one of those exceptions. If that fails, then it would be appropriate to consider the charter amendment."