Prince George's County Executive Winfield M. Kelly Jr. has suspended $21 million in planned construction projects, including medical clinics and libraries, as the first step to impress citizens and the state legislature that without a change in tax laws he can not pay for next year's budget.

Althougt Kelly vowed last Friday that he was "quite serious" about the construction curtailment, he also refused to rule out a restoration of the projects at some later date.

Each year, as the legislature opens and local officials begin balancing their budgets, the state erupts in a flood of dire budget predictions. By the time the legislature session ends in April the threatened disasters have often disappeared adn the counties and cities continue governing with few significant changes.

Kelly said he wants the state legislature to pass his proposal to allow the county to divide its property tax into three separate categories with separate rates. This "tier tax," Kelly said, will allow the county to tax apartment buildings at a higher rate without raising the taxes of single-family homes or industrial property.

He also said that he could accept alternative changes like increasing the county's share of the state income tax or sharing any increase in the state sales tax with the county.

All three alternatives, however, are unpopular with the state legislators.

With Council members and his staff surrounding him, Kelly said at his Friday press conference that this was only one in a series of "dramatic measures" he will take to avoid a large increase in the county's property tax.

"I think there will be a major protest against this action suspension of programs . . . but the people have been telling me the they do not want to rely on the (residential) property tax to finance all government services," Kelly said.

Apartments owners, on the other hand, have been bitterly complaining over the past two years that Kelly is trying to shift the burden of paying for county services from the homeowner to them.

Kelly held up the construction of some 18 buildings and the repair of construction of 62 roads, bridges, and rail facilities by refusing to sell $21.2 million in county bonds next February. He also asked the Maryland National Park and Planning Commission to cancel its plans to purchase or renovate some 18 pieces of property.

County officials had planned to sell the $21.2 million in bonds in New York on the first week in February. Only $5.9 million worth of bonds will be sold next year to pay for projects the county must construct because of previous contracts, Kelly said.

Kelly did not have his completed budget at the press conference. He said it would not be ready until mid-January but he said he knew enough to begin making budget cuts.

He blamed the county's problems on the low return the county earned on its investments this year and on the amount of taxes the county received from its tenant tax.

Together, the two revenue sources were $2 million short of last year's estimate. This is about the same amount the county would pay in interest for the bonds it had planned to sell.

If Kelly does not reverse his decision, communities like Glenarden and Beltsville will not have libraries. A $3 million addition to the county jail will not be build. Medical clinics promised TO Oxon Hill, Clinton and Bowie will also be shelved.

"We hope the citizens will rally behind out demand for a change in the tax structure," said John A. Lally, a Kelly aide. "We've tried and faild for two years to get a change and it has to come this year. Next year is an election year and no one will want to talk about change."