(Adds election totals)
By Alwyn Scott
NEW YORK, May 9 (Reuters) - The International Association of Machinists and Aerospace Workers, one of North America's largest industrial unions, re-elected its leaders by a two-to-one margin on Friday, the union said.
The decision ends the first serious challenge to the leadership of the union, known as IAM, in more than 50 years, and signals a shift away from the challengers' reform drive.
Members "overwhelmingly rejected an effort to move this union backwards and we now turn our full attention to moving the IAM forward," IAM International President R. Thomas Buffenbarger said in a statement.
The challengers said they planned to dispute the results with the U.S. Labor Department. They questioned the validity of thousands of votes and alleged the incumbent leaders intimidated voters and used union funds for campaigning.
"We intend to ask the Department of Labor to investigate these serious violations, through every avenue available to us," said Jay Cronk, who ran for international president against Buffenbarger.
At stake in the election was the leadership of 332,000 dues-paying union members, including about 32,000 Boeing Co workers and others in jobs as diverse as airline ticket agents, wood workers and lobstermen in Maine.
Members cast 23,545 votes for Buffenbarger compared with 11,163 for Cronk. General Secretary-Treasurer Robert Roach, Jr was also re-elected with 23,828 votes received compared with 10,690 for challenger Dale Cancienne.
The eight vice president positions up for grabs all went to incumbents, though three of them were also listed on the slate of reform candidates. (Reporting by Alwyn Scott; editing by G Crosse and Paul Simao)