Colorado politics just got fracked up.

Democratic Sen. Mark Udall announced his opposition Wednesday to statewide ballot initiatives being bankrolled by Rep. Jared Polis that would impose restrictions on hydraulic fracturing, or fracking. Udall is facing a tough fight from GOP Rep. Cory Gardner, who has slammed the ballot effort, to maintain his Senate seat.

"Colorado has served as a model for the nation on finding the right balance between protecting our clean air and water, the health of our communities, and safely developing our abundant energy resources. In my view, these proposed ballot initiatives do not strike that balance," Udall said.

Udall's move was compelled partly because Democratic Gov. John Hickenlooper, also up for re-election this year, canceled a special legislative session that aimed to shelve the Polis-pushed proposal. The ballot proposals are likely headed for the November ticket. Hickenlooper was trying to secure buy-in from legislators and drilling companies to add new standards to landmark methane emissions regulations for fracking his administration implemented in February, which were the first such standards in the nation.

Gardner's campaign for months had pressed the incumbent Udall to take a stand on the measures. The race, in many respects, has been based on energy issues and, to a broader extent, support of the state's oil and gas industry that has been buoyed by fracking.

"Welcome to the party, where have you been?" tweeted Chris Hansen, Gardner's campaign manager.

One ballot proposal seeks to extend the setback for fracking wells to 2,000 feet from existing buildings -- four times the current limit -- that detractors say would take a lot of Colorado land off the market. The other ballot proposal would establish a so-called environmental bill of rights in which the more restrictive of conflicting state and local laws takes precedence.

Now there is little difference between the lawmakers on energy issues. When reached for comment, Gardner campaign spokesman Alex Siciliano urged Udall to support the Keystone XL oil sands pipeline. Udall voted against the project last month in committee because he said the State Department should be allowed to finish its review of the Canada-to-Texas project, which has been in administrative limbo nearly six years awaiting a State Department decision regarding a cross-border permit.

The fracking ballot proposals have clouded the Senate race, along with Hickenlooper's, for months.

Polis is said to have poured millions into the twin ballot proposals through a group called Coloradans for Local Control, which made a $1.45 million donation on May 9 to pro-ballot group Coloradans for a Safe and Clean Energy. The Colorado Office of Administrative Courts on Monday denied a campaign finance ethics complaint from business-backed Coloradans for Responsible Reform against the groups for not disclosing its list of donors.

"The complainant alleges that Local Control failed to report the contributions it presumably received to fund the transfer. But there was no evidence that Local Control received any contributions subsequent to a time it was required to report them," administrative law judge Matthew E. Norwood wrote in the decision.

Polis spokesman Scott Overland, along with Mara Sheldon, a spokeswoman for Coloradans for a Safe and Clean Energy, confirmed to the Washington Examiner that Polis is a contributor.

Polis, in a statement, said he supported a legislative compromise that appeared in reach after negotiations between Hickenlooper, lawmakers, oil and gas firms active in the state and others. The terms included deals on setbacks, and also would have prohibited outright fracking bans within cities and towns. But the proposal drew criticism from the American Petroleum Institute and other firms, saying it could produce a chilling effect on investment in the state.

Polis said "out-of-state organizations" spooked lawmakers into backing down from the pact.

"When they began their work, they all knew that the chances of success were slim, but that the effort was worth it. Unfortunately, special interests and out-of-state organizations, worried only about politics and partisanship turned this into a battle of personal attacks and scare tactics," Polis said, adding that now "we must turn to the people of Colorado to solve this problem."

Sheldon noted that both ballot initiatives have picked up more than half of the 86,105 signatures each need by the Aug. 4 deadline, adding that she expects the signature count "to be considerably higher" when Coloradans for a Safe and Clean Energy releases its new numbers Thursday.

Overland also rejected claims that the ballot push would negatively affect Udall, Hickenlooper or other Colorado Democrats.

"There hasn't been any sort of firm evidence that this is bad for Democrats. We think this could be bad for Republicans and drive a lot of Democratic turnout," he told the Examiner.

Polis has been vocal on fracking safety standards, though he says he supports the drilling method, which blasts a high-pressure mixture of water, sand and chemicals into tight-rock formations to access hydrocarbons buried deep underground.

Last July, Polis threatened to sue a drilling company for sidling up too close to his Weld County home, but later dropped the lawsuit. He, with some public health and environmental groups, has concerns about potential groundwater contamination from fracking and has said drilling sites decrease property values.

The oil and gas industry has opened its pocketbooks to beat back the proposals.

Anadarko Petroleum and Noble Energy, a pair of independent drillers, banded together to fund Coloradans for Responsible Energy Development to raise awareness about the proposals, though how much they have spent on the effort isn't publicly available. Protect Colorado, another pro-fracking group, has raised $6.1 million through June 25, according to state records.

"With the November election fast approaching, we must turn our attention to defeating adverse ballot measures. If approved by voters, they would become constitutional amendments that leave no room for accommodating unique community needs or special situations and risk tens of thousands of jobs, billions of dollars of investments, and hundreds of millions of dollars in local and state tax revenues," a group of energy firms, led by Anadarko and Noble, said in a letter Wednesday.

Karen Crummy, a spokeswoman for Protect Colorado, added, "Congressman Polis refused to make any concessions and held Coloradans hostage for weeks with his 'my way or the highway' ultimatum," saying that she's "confident" voters will reject the "arbitrary and irresponsible" proposals if they make it onto the ballot.

A poll conducted by Benenson Strategy Group, funded by Coloradans for a Safe and Clean Energy, conducted in May but released this month found the setback initiative would pass 64 percent to 21 percent, though support fell to 56 percent when respondents were read negative claims about the initiative. For the second, unadulterated support was 64 percent compared with 27 percent opposed, but fell to 52 percent after hearing negative comments.

Coloradans for a Safe and Clean Energy, which supports the ballot proposals and has raised $1.45 million through June 25, pinned the blame on the oil and gas industry for failing to strike a deal on regulations to shelve the ballot initiatives.

"It is unfortunate, although not unsurprising, that Big Oil and Gas and their industry allies could not come together on legislation that would balance the safety of our children and communities from industrial fracking activities near homes, schools and hospitals," Sheldon said.