In this March 25, 2014 photo, heat from machinery distorts the air as a worker watches over a hydraulic fracturing operation at an Encana Corp. oil well near Mead in Weld County, Colorado.

(AP Photo/Brennan Linsley)

Oil and gas companies are the top political contributors so far this year as they prepare to battle anti-fracking initiatives in 2016. 

Environmental coalitions have already formed and stated their intentions of putting a number of initiatives on the 2016 ballot, said Karen Crummy, a spokeswoman for the pro-energy group Protect Colorado.

"So it stands to reason that we would want to be prepared for next year," Crummy said.

Crummy's group has received $1.6 million in contributions from the state’s largest drillers already this year.

One new group – Coloradans Resisting Extreme Energy Development --  says it plans to advance several ballot initiatives. That includes one that would allow cities and counties to ban fracking.

Trisha Olson, who heads the group, is not surprised oil and gas companies are raising money for a fight.

"They will spend huge sums of money," Olson said. "In some of the local campaigns, they outspent the grassroots 500 to one."

There are no reported contributions yet supporting the potential ballot initiatives.