The power struggle for control of the Teamsters, America's biggest union, began before Jackie Presser's death and is complicated by the unprecedented government attempt to take over the union.

The union's secretary-treasurer, Weldon Mathis, is favored to succeed Presser as president, but he faces internal opposition and possible challenges by several rivals, sources said Monday.Presser, 61, died of heart failure Saturday after a long battle with obesity, cancer and heart problems. He was to be buried Tuesday in Cleveland.

The struggle for control of the 1.6 million-member union already was under way when Presser took a four-month leave of absence in May because of poor health.

The 17 remaining members of the Teamsters Executive Board must meet within 15 days to select a new president.