The debate over banning fracking in Colorado presents an "existential threat" to the game-changing oil and gas drilling method that has made the U.S. a top energy producer in just a few years, Sen. Cory Gardner said Thursday.

The Colorado Republican discussed the issue at the Colorado Oil and Gas Association's 28th annual energy summit that wrapped up Thursday in Denver. Environmental groups are pushing a number of state ballot initiatives to give local authorities the power to ban fracking.

"This debate that's taking place in Colorado right now about whether or not we should ban fracking is an existential threat that we have to kill and we have to stop," Gardner said. "But unfortunately, it's not just a debate that's taking place in Colorado."

Anti-fracking activists have managed to offer two ballot initiatives to be considered in November when voters go to the polls to choose the next president. Beyond the state initiatives, Democratic nominee Hillary Clinton has talked about a national ban. Until this week, Republican nominee Donald Trump had said he supported local and state authorities' right to ban the drilling method.

Coincidentally, oil and gas mogul Harold Hamm, a confidante to Trump, addressed the conference earlier in the week, but not before he told the Wall Street Journal that the nominee doesn't support a ban on fracking.

Democratic Colorado Gov. John Hickenlooper had criticized Trump earlier this month for saying he supports a ban. "I don't think he understands, completely, the issue," Hickenlooper said in an interview with the Denver Post. "But that's not unusual for him."

Gardner chose to poke at Clinton, not Trump, on the issue, citing a new report by the Chamber of Commerce detailing her support for banning the practice.

"We've heard at least one of our presidential candidates say, Hillary Clinton said, in this Chamber of Commerce report and I hope you take a look at it — it just came out — 'no future extraction on federal lands. I agree with that,'" he said.

"Think about what that means to jobs in this state. I grew up in a little town with 3,000 people. Thanks to the natural gas industry, we have a third stop light in that little town. We had two. Now we have three."

He said without energy development, many small towns like the one he grew up in shrivel up and fall apart economically. "I can tell you that, as 67 kids who graduated in my high school class, very few of us actually returned home to be in that small town again. Because there were no jobs, no economic opportunities, there were no good benefits that came along with any job you could find."

However, when natural gas started to pick up in the state, "my classmates started moving back," he said. "People who graduated from high school and college were returning to that small town, were staying in that small town."

The chamber report he discussed is the first in a series on "energy accountability." The report examines the cost of Clinton's policy proposals on banning oil, gas and coal production on federal lands. It concludes that the policies would cost hundreds of thousands of jobs and billions of dollars in lost revenue.