A fight over several key county appointments yesterday ended the first attempt by the new chairman of the all-Democratic County Council to ease hostilities with the Republican county executive, Lawrence J. Hogan.

Hogan withdrew the names of two nominees to the Washington Suburban Sanitary Commission after council members made it clear they would reject his preferred nominee. Later in the day, the council rejected another Hogan nominee, this one to the Maryland-National Capital Park and Planning Commission.

Council Chairman Gerard McDonough, a seven-year council veteran and a past leader of council opposition to Hogan, helped arrange the appointments with Hogan. He chastised the council for refusing to cooperate with the county executive.

"The executive has made a good faith effort to initiate an era of cooperation with the council," said McDonough. "I don't see that good faith effort on the council's part."

Despite McDonough's urgings, the council voted 7 to 4 to reject the nomination of Larry F. Hoffman to the park and planning commission. Hoffman, an insurance broker and a member of the Prince George's County Republican Central Committee, was slated to replace University of Maryland Professor John Churchill, another Republican, whose term had expired. Under the county charter, Churchill will serve until replaced.

Lawrence Hogan Jr., Hogan's son and appointments aide, said that he, and not the county executive, decided to withdraw both names yesterday upon the request of one nominee, Lanham attorney Dale L. Jernberg, former president of the National Bank of Washington.

Jernberg, a Republican, had been selected by Hogan to replace Democrat Johanna Norris on the WSSC, but he asked that his name be removed after learning that a majority of the council opposed his appointment. Hogan also withdrew the name of the other nominee, Democrat Andrew Vislosky, a WSSC commissioner whose term expired three years ago, although he has continued to serve. Hogan nominated the pair last month, ending a three-year effort to replace Vislosky with a Republican.

He agreed to renominate Vislosky in an effort to persuade the council to replace Norris with a Republican.

The council's refusal to confirm the nominees will erode the already strained relations between the executive and council, predicted Hogan Jr. "You can't have cooperation when it's only on one side," he said.

Hogan's withdrawal of the names and the council's rejection of Hoffman reflected McDonough's failure to win council support in his first test of leadership as chairman of the 11-member council. Several council members and state legislators had opposed the efforts to replace Democat Norris, and there were threats by Democratic Sens. Edward Conroy and Michael Donovan to try to end the council's power to appoint WSSC members.

McDonough was unable to persuade them that cooperation with Hogan was worth the price of removing Norris.

McDonough attributed his defeat to his decision to bargain for the appointments openly.