In an attempt to move Prince George's County's union negotiations from the political arena, county executive Lawrence J. Hogan yesterday sent employes a letter emphasizing his desire to resolve a controversial contract dispute which could lead to a strike by 1,500 county workers.

The letter, which was inserted in the paychecks of all workers represented by the American Federation of State, County and Municipal Employes, denied that political considerations had caused Hogan to reject a tentative contract agreement signed by his negotiatiors and the unions. That agreement was, by all accounts, favorable to the county.

He wrote, instead, that the agreement had included three economic issues he did not want to approve, forcing him to veto the contract.

The county and five locals in the federation have been trying to negotiate a new contract for the last year. Since July, the county employes who operate snow plows, repair county roads, guard the county jail and provide secretarial services to every county office, have been without a contract and have not received the yearly cost-of-living increase given other county workers.

Last week, the dispute appeared to be resolved when Hogan's negotiating team and the union signed a tentative agreement which gave the employes a 4.7 percent wage increase this year and 5 percent next year.

However, Hogen rejected that contract, a decision that several sources said was due to his anger at recent criticism of him by the county council. The sources also said Hogen was concerned that if he signed the agreement it would appear he had capitulated to council and union pressure.

In yesterday's letter, Hogan said he rejected the tentative contract because of several provisions relating to leave time and medical coverage costs.

In the tentative contract, negotiators for the county agreed to have Prince George's pay up to 90 percent of the cost of some minor medical coverage. Hogan said he authorized only 85 percent.

The tentative agreement also called for the county to pay a one-time bonus and provide one personal leave day to union members in exchange for two hoidays they now have that do not conform with the rest of the county employes' holidays. Hogan said he did not want to pay the cash bonus.

The agreement also provided union members with a nontaxable cash bonus to make up for the cost-of-living increases they did not receive in July when their contract expired. Hogan said the county does not have the power to make the bonus nontaxable.

Hogan declined to talk to reporters yesterday about the letter or the negotiations.

Union representative Paul Manner said yesterday, "The letter makes Hogan look silly. It just shows how small the differences between [the two sides] are and reconfirms the belief that he was just [vetoing the tentative contract] for political reasons."

The county's negotiators and the union are scheduled to meet with a federal mediator Tuesday to attempt once more to resolve the contract dispute.