Kansas Governor Sam Brownback speaks during a campaign rally at New Steel and Pipe Supply in New Century, Kan., Monday, Oct. 27, 2014. Brownback is running for reelection against Democratic candidate Paul Davis.

Topeka ? A protest by Kansas regulators against federal efforts to limit carbon emissions is giving Republican Gov. Sam Brownback an opportunity in the final days of his close re-election race to tie his Democratic rival to President Barack Obama.

But Democratic challenger Paul Davis on Thursday accused the federal Environmental Protection Agency of “shoving those rules down our throats.”

Davis’ comments came a day after the Kansas Corporation Commission, which regulates utilities, asked the EPA to withdraw its proposed rule for limiting emissions from power plants of heat-trapping gases linked to global warming, such as carbon dioxide.

The commission’s staff plans to file a 40-page report criticizing the rule and suggesting it could boost electric rates by 30 percent or more. However, a leading Kansas environmentalist expressed skepticism Thursday about the conclusions.

Brownback appointed the commission’s three members, and the conservative governor is a vocal critic of the EPA’s proposed rule, which is set to take effect in June 2015. He argues that Democratic challenger Paul Davis wouldn’t fight the rule if he’s elected — something Davis’ spokesman strongly disputed.

Their race appeared to be a toss-up heading into Tuesday’s election, with Davis courting disaffected moderate Republicans and unaffiliated voters. Brownback and his allies portray Davis as an Obama-supporting liberal to undercut his challenger’s appeal in the GOP-leaning state where the president received only 38 percent of the vote in 2012.

“I think we’ve got to constantly push back against an Obama administration that’s got a war on middle America,” Brownback said. “I’m doing that, and Paul Davis isn’t.”

Davis said during a campaign stop in Wichita that he’d seek a “meaningful conversation” with the federal government.”

But he added, “We seem to have the EPA telling the states what to do all the time.”

In an effort to push Brownback to victory, the Republican Governors Association began running a television ad Wednesday saying voters who like Obama will love Davis, though it didn’t mention the EPA rule. Davis was an Obama delegate to the 2008 and 2012 Democratic national conventions.

The EPA contends that its rule would give states flexibility by setting targets for reducing emissions by 2030. The federal agency has estimated that Kansas would have to cut emissions from power plants from 2012 levels by 23 percent.

But coal-fired power plants generate more than 60 percent of the state’s electricity, and the KCC report said the only feasible way to comply with the rule and maintain a reliable flow of electricity would be to build new gas-fired generators with technology not in use in Kansas.

The report predicts the resulting costs would force electric rates to rise within the “conservative range” of 10 percent to 30 percent. The additional costs to ratepayers would range from $5 billion to $15 billion, the report said.

Moti Rieber, an Overland Park rabbi and director of the environmental group Kansas Interfaith Power & Light, chided the KCC for mentioning climate change only in a single footnote in the report. He said electric rates were already going to rise as utilities upgraded their plants, even if they stuck with “outdated” coal-fired generators.

“So, as long as we’re going to have to make investments in our electric utility system anyway, the question becomes, what do want our rates to be paying for?” he said.