Teamsters President William J. McCarthy has told associates he will not seek reelection, clearing the way for members of the union's executive board to choose a slate of candidates for the union's first government-supervised direct elections next year, union sources said yesterday.

Although McCarthy has made no official announcement, sources said he gave the go-ahead Monday for supporters on the International Brotherhood of Teamsters' 17-member board to assemble a slate without him. The board is meeting in West Palm Beach, Fla.

McCarthy, 71, who headed the New England Conference of Teamsters before his surprise selection by the board to succeed the late Jackie Presser two years ago, has presided over an increasingly chaotic political situation for most of his term. He is now in poor health following open-heart surgery and a minor stroke.

The union elections, to take place in three stages between now and December 1991, were ordered as part of an agreement the Teamsters board reached last year to settle a massive civil racketeering suit in which the Justice Department charged that the Teamsters had become what amounted to a wholly owned subsidiary of organized crime.

Two union vice presidents, R.V. Durham of North Carolina and Arnie Weinmeister of Seattle, appear to be the front-runners to replace McCarthy atop the board's slate. Weinmeister, a Hall of Fame former lineman for the New York Giants, is better known, but sources said McCarthy favors Durham for the presidency.

McCarthy let it be known he would not seek reelection after engineering the removal of political rival Joseph Trerotola as director of the powerful Eastern Conference of Teamsters.

The vote against Trerotola, 81, who remains the union's first vice president, was seen as a test of strength and unity for the more moderate members of the board, who have been seeking to form a unity slate in the first direct, secret-ballot elections in Teamsters history.

Under the agreement with the Justice Department, delegates will be selected at the local union level to the Teamsters convention in Florida next June. Those delegates will nominate candidates for the rank-and-file election in December 1991.

A Teamsters source said yesterday that McCarthy decided to make his move now because "this is the time and this is the place" if the board was going to preempt any challenge to its authority.