Freshman GOP incumbent Chip Cravaack, facing a potentially stiff challenge in November to keep the congressional seat he won from DFL stalwart Jim Oberstar in 2010, is getting a big boost from a Minnesota-based labor union. The International Union of Operating Engineers Local 49 announced Thursday that it is endorsing Cravaack after a vote of the union's 8th District members who heard from Cravaack and all three contenders in the Aug. 14 DFL primary. Cravaack, a former airline pilot, has been courting the 49ers for some time, emphasizing his support for mining jobs on the Iron Range and Davis-Bacon prevailing wage legislation. Said Jason George, Legislative and Political Director International Union of Operating Engineers Local 49: "The members of Local 49 have spoken."