The United Mine Workers will elect officers Nov. 9, and analysts see possible labor trouble ahead for the coal industry no matter who wins.
Sam M. Church Jr., the UMW's president, faces a strong challenge from Richard L. Trumpka, a young union lawyer who is showing unexpected strength.
The original issues in the contest included widespread miner dissatisfaction with the 1981 labor contracts negotiated under Mr. Church's leadership. Recently those issues have been overshadowed by a battle over charges by Church that his opponent is ineligible for office in the union.
Under the UMW's constitution, national officers must have worked five or more years in mine jobs under the union's contract. Mr. Trumpka, little known until he began campaigning for office last winter, says he has ''irrefutable evidence'' that he worked seven years in mine jobs.
Church, with an unchallenged 17-year work record, charges that his opponent's record is based on fraud and forgery. He says that Trumpka worked, at most, four years. Trumpka brands such charges as ''the act of a desperate man who is losing the election.''
The credibility of the two men has thus become a major issue and campaigning has been thrown into turmoil.
Ordinarily, the union's four election tellers settle eligibility disputes. But they are evenly split between the candidates. Action on the charges is considered unlikely before the voting by UMW's 170,000 members in 877 locals.
If Trumpka wins, a federal investigation and court challenge of his right to the presidency are considered inevitable. Should he lose, he probably will seek a federal probe of the incumbent for his campaign tactics, with a suit also likely. Either way, the union leadership could be thrown into disarray for months.
This would not be unusual for the current UMW. Once strongly led by John L. Lewis and then less effectively by W. A. (Tony) Boyle, the union's centralized control has been weakened by years of ''reform'' or insurgent leadership. The UMW is now a divided union, with considerable power in the hands of ambitious regional officers.
When candidates for the coming elections sought nominations from locals, Trumpka received support from 61 percent of the 877, to 39 for Church. The challenger said his strength included ''most of the big working locals.'' He called this ''a tremendous victory for rank-and-file miners disillusioned with Mr. Church's reactionary leadership.''
Church, appointed to the presidency in November 1979 by the executive board, worked hard in the last bargaining round for a settlement that would give miners substantial gains. But at the same time he helped the coal industry stablilize its labor relations and hold down costs - thus giving it a firmer basis for enlarging the coal market.
The terms were not popular in the coal fields. Church, like his predecessor Arnold R. Miller, who resigned in 1979, was criticized for bargaining incompetence and lack of militancy.
While no contract negotiations are scheduled before late 1983 or early '84, the UMW has a tradition of illegal walkouts that cause major disruptions of coal production.
If the election results are close, as expected, the winner may find it hard to exercise the authority needed in a rebellious union.
In the longer range, because bargaining is a critical factor in union politics, both Church and Trumpka are likely to react more aggressively in relations with employers. Cooperative efforts to reinforce the industry could be at an end.