In the fight over Colorado’s hydraulic fracturing future, environmental advocates received a major blow last month when an initiative to ban natural gas extraction didn’t gather enough signatures to make it on the November ballot. Now, their oil and gas industry-backed adversaries in that fight are looking to a new initiative that would make any ban even harder to achieve.

A group that raised nearly $17 million to fight anti-fracking activists this year shuffled at least $1 million earlier this month to support a ballot initiative that would make it difficult to change the state constitution, according to a report published Tuesday by Colorado Public Radio. Doing so would make passing new fracking restrictions that rely on those changes much more challenging.

Protecting Colorado’s Environment, Economy and Energy Independence — a committee funded mostly by gas companies Anadarko Petroleum and Noble Energy — gave that $1 million to a political committee known as Raise the Bar on Sept. 8, roughly 10 days after the ban initiative failed. Democratic Gov. John Hickenlooper publicly supports Raise the Bar, an organization that favors the initiative known as Amendment 71 and is against changing the state constitution.

Energy companies like Anadarko Petroleum have a lot to lose in Colorado. The company invested around $10 billion in the state between 2010 and 2015, according to their website. That investment has allowed it to buy up 350,000 acres of land that it estimates has enough natural gas to equal roughly 1.5 billion barrels of oil.

Noble Energy’s website says it invested $2.3 million into Colorado in 2015 and paid roughly $120 million in taxes to the state that year.

Fracking is a natural gas drilling method that drills into the ground and then injects high-pressure water mixtures into the Earth to release gas from rocks inside. Proponents argue that the gas is a cheap and cleaner alternative to traditional fossil fuels while opponents say that chemicals in the water mixtures are dangerous and argue the drilling can cause earthquakes, among other concerns.