The International Association of Machinist and Aerospace Workers (IAM) is lobbying mechanics at United Airlines and collecting cards in an attempt to demonstrate a majority of workers want to switch unions. Incidentally, UA mechanics have been the center of many union organizing efforts. Though they are currently represented by the International Brotherhood of Teamsters, they were part of the Aircraft Mechanics Fraternal Association before that, and actually part of the IAM before that. Now the IAM is trying to win back UA mechanics ? but (due to certain labor regulations) the earliest the vote to switch could happen is in 2010. The Teamsters have called the IAM campaign "an act of desperation".
See "IAM aims to win United Airlines mechanics, again", Joshua Freed, May 7, 2009