BOZEMAN, Mont.  With his electrician’s tool belt and company logo cap, Rick Schmidt looks every bit the small-business owner he in fact is. That he often reeks of marijuana these days ... well, it is just part of the job, he said.

“I went on a service call the other day  walked in and a guy said to me, ‘What have you been smoking?’ ” said Mr. Schmidt, 39.

For Gallatin Electric, a six-employee company founded by Mr. Schmidt’s father, Richard, as for other businesses in this corner of south-central Montana, medical marijuana has been central to surviving hard times as the construction industry and the second-home market collapsed. Not the smoking of it, the growing of it or even the selling of it, but the fully legal, taxable revenues being collected from the industry’s new, emerging class of entrepreneurs. Three of the four electricians on staff at Gallatin, Mr. Schmidt said, are there only because of the work building indoor marijuana factories.

Questions about who really benefits from medical marijuana are now gripping Montana. In the Legislature, a resurgent Republican majority elected last fall is leading a drive to repeal the six-year-old voter-approved statute permitting the use of marijuana for medical purposes, which opponents argue is promoting recreational use and crime.