BOZEMAN, Montana - Medical marijuana has been central to surviving hard times here as the construction industry collapsed, thanks to the fully legal, taxable revenues being collected from a new class of entrepreneurs. But questions about who really benefits from medical marijuana are gripping Montana. In the Legislature, a resurgent Republican majority is leading a drive to repeal the six-year-old voterapproved statute permitting the use of marijuana for medical purposes, which opponents argue is promoting recreational use and crime.

The bill received its first hearing in the Senate Judiciary Committee on March 25. If it succeeds, Montana would be the first to reverse itself among the 15 states and the District of Columbia that have such laws.

In Bozeman, a college and tourism town north of Yellowstone National Park, the interconnection of economics and legal drugs extend in every direction, business people say.

Marijuana growers buy equipment from gardening supply companies; mainstream bakeries contract for pot-laced pastries; and even the state’s biggest utility is seeing a surge in electricity use by the new factories. Medical marijuana has roughly quadrupled in Montana in the last year.

“It’s new territory ,” said Brad Van Wert, a sales associate at Independent Power Systems, which has completed its first solar installation for a medical marijuana provider called Sensible Alternatives.

He said that marijuana entrepreneurs were responding to the appeal of a 30 percent tax credit offered by the state for expansion of renewable energy.

Growers and providers say that even though regulations enacted last year restricted their numbers, they also created a climate of legitimacy.

An industry group formed by marijuana growers estimates that they spend $12 million annually around the state, and that 1,400 jobs were created mostly in the last year in a state of only 975,000 people.

Rob Dobrowski, a construction contractor until the recession hit, said he now employs 33 people at his marijuana business, including his two brothers, also formerly in construction.

“Somewhere around 25 people have made anywhere from a $60,000 to a $100,000 bet on this industry,” said Bozeman’s mayor, Jeff Krauss, a Republican, referring to the local startups and their capital costs.

“Now the Legislature has got us saying, ‘Ha, too bad, you lose,’ ” Mr. Krauss added. “Boy, is that a bad message to send when we’re in the doldrums.”

One business owner here estimated that a person could essentially buy a job for $15,000, beginning a small growing operation with 100 plants.

For construction trade workers who were self-employed before the recession, the owner said, the new industry feels familiar.

“Forty to 50 percent of customers come from construction,” said the owner. “Plumbers, electricians, the whole genre of workingclass, blue-collar Montana.”

The work force includes people like Josh Werle, 29, who took a job as a grower at a company called A Kinder Caregiver after work as a commercial painter dried up.

Mr. Werle, a fourth-generation Montanan, said his family had seen many industries fail over the decades. The economy, he said, finally pushed him out.

Another grower, Tara Gregorich, 29, graduated last May from Montana State University with a degree in environmental horticultural science. “I never envisioned myself working in this,” she said. “But this is one of the few industries in Montana that is year-round.”

By KIRK JOHNSON