Gubernatorial candidates Walker Stapleton and Jared Polis traded barbs Tuesday over Colorado’s setback requirements for oil and gas operations – and got in a few insults for good measure.

Stapleton, the Republican state treasurer who launched his campaign over the weekend, threw a punch at Polis, a wealthy Democratic congressman, when the topic came up during an interview Monday with a Denver television station.

Asked by Fox31 reporter Joe St. George if he supports any setbacks or restrictions on drilling, Stapleton fired back: “Let me tell you, I am terribly fearful that this election cycle the oil and gas industry is under attack. We have a leading candidate on the Democratic side, Jared Polis, who is literally running to kill the oil and gas industry in Colorado – which would cost us, by the way, approximately $30 billion to Colorado’s economy and 230,000 jobs.”

Polis, a longtime critic of the fossil fuel industry, wants Colorado utilities to use 100 renewable energy by 2040 – it’s a central platform of his campaign – and financed 2014 ballot initiatives that oil and gas advocates warned could have shut down the industry entirely.

In response to Stapleton’s attack, Polis told St. George, “If Super Pac Stapleton doesn’t believe families should have a say in what goes on in their own backyards, he shouldn’t be running for governor of Colorado.”

Stapleton has come under fire from some quarters for helping a super-PAC style committee rake in vast sums to support his candidacy before he got in the race – a spokesman for the Colorado Democratic Party called the arrangement a “shady fundraising scheme” on Tuesday – but his advisors dismiss the complaints as baseless.

Soon after St. George tweeted Polis’ comment, the Stapleton campaign tore into Polis in a release.

“Congressman Polis’ agenda is clear, he has been working for years to destroy the 230,000 jobs that oil and gas supports, all to appease his base of Bernie Sanders acolytes at the expense of hardworking Coloradans,” the Stapleton crew said. “Clearly the Congressman has spent too much time in Washington D.C and needs to readjust to the altitude in Colorado.”

Stapleton’s GOP primary opponents are 18th Judicial District Attorney George Brauchler, entrepreneur and former state lawmaker Victor Mitchell, former investment banker and Mitt Romney nephew Doug Robinson, former Denver County Trump campaign co-chair Steve Barlock, former Parker Mayor Greg Lopez and Larimer County Commissioner Lew Gaiter.

At least four more Republicans have said they’re considering joining the field: Attorney General Cynthia Coffman, former U.S. Rep. Tom Tancredo, former CSU Athletic Director Jack Graham and businessman Barry Farah.

Along with Polis, the Democrats in the race are Lt. Gov. Donna Lynne, former state Sen. Mike Johnston, former state Treasurer Cary Kennedy and businessman Noel Ginsburg.

Democratic Gov. John Hickenlooper faces term limits after next year’s election.