The ability of super PACs and advocacy groups to paint Ohio Democratic Senate candidate Ted Strickland, a coal region native, as an opponent of the coal industry has helped to turn a once-close contest into a near-runaway for incumbent Republican Rob Portman.

Outside groups have spent $32 million, most of it since May, to re-elect Portman, outspending the organizations supporting Strickland by a 2-1 margin. Nearly 40 percent of Portman's windfall came from the Freedom Partners Action Fund and Americans for Prosperity, two groups in the billionaire libertarian Koch brothers' network of political nonprofits, an analysis of Federal Election Commission disclosures shows.

Over the years Charles and David Koch have waged a battle on multiple fronts to undercut climate science, environmental regulations and clean energy.

Their opposition is not only ideological. The brothers' Wichita, Kan., conglomerate, Koch Industries, includes oil refineries, pipelines, chemical and fertilizer manufacturing facilities,and ethanol plants—businesses that would be profoundly affected by policy to curb fossil fuel use.

The ads funded by the Koch brothers' groups blame Strickland for Ohio's loss of 350,000 jobs and its budget collapse when he was governor—a tenure during which the state was hard hit by the 2008 financial crisis and recession. They hit him for state subsidies received by a solar company that planned an Ohio plant, but never built it. And they criticize the job he took after he lost his bid for re-election as governor—a job heading the progressive Center for American Progress, a think tank that supports climate policy and was founded by Hillary Clinton's campaign manager, John Podesta.

"Ted Strickland left Ohio to lead an anti-coal group in Washington, D.C," says a Freedom Partners ad. "Ted Strickland's dream job was a nightmare for Ohio coal jobs."

Freedom Partners also quotes the Ohio Coal Association as saying Strickland was "bad for coal."

The anti-coal drumbeat took its toll on Strickland's chances, said Mark Shanahan, a clean energy consultant in Columbus, who served as Strickland's top energy adviser when he was governor.

"To the extent that they [the ads] are energy related, they've been mostly targeted at southeast Ohio and the coal issue, which has been successful in getting the mine workers to endorse Portman," Shanahan said. "And it's insane to think of someone like Ted Strickland as being anti-coal."

"It's a comprehensive bombardment," said University of Cincinnati political scientist David Niven, a former Strickland staffer. "It's on TV. It's online. It's tucked into the free coupon giveaway flyers they stuff under the doormat."

Freedom Partners and Americans for Prosperity did not respond to repeated requests for comments.

The big spend by the Koch groups underscores an electoral strategy aimed at keeping GOP control of the U.S. Senate, no matter who wins the White House. Charles Koch told reporters in August that his first priority was "to preserve the country's financial future and to eliminate corporate welfare."

"Since it appears that neither presidential candidate is likely to support us in these efforts," he said, "we're focused on maximizing the number of principled leaders in the House and Senate who will."

The contest in Ohio is among 10 Senate races that could determine whether the GOP maintains its majority.

After the money flooded into a race that was neck-and-neck last April, Portman now holds a 51-40 advantage among likely voters, according to a Sept. 9 Quinnipiac University poll. The Koch organizations announced earlier this month that they are not going to buy any more ads in Ohio because they feel Portman's lead is safe—a far cry from May when a Quinnipiac poll showed that 40 percent of Ohio voters did not know him.

"The frustrating thing about this campaign is at the beginning of it, Portman had very low name recognition in this state—no one knew who he was or what he did about anything—which is amazing for a sitting U.S. Senator," Shanahan said.

The fusillade has had collateral impact, too: Despite the Koch brothers' resolve to stay out of the presidential race, observers say their spending spree is helping Trump, who pulled ahead of Democratic nominee Hillary Clinton in Ohio polls for the first time in the past few weeks.

But the clearer impact was on the opinions of the two candidates, which swung dramatically over the summer.

"The attack ads from the outside groups against Strickland allowed Portman to go on an offensive driving up his own positives," said Daniel Birdsong, political science professor at the University of Dayton. "Meanwhile, the outside groups were hammering Strickland, reminding people of his time as governor."

Microcosm of Nation's Energy Debate

In addition to its well-known history as a presidential bellwether state, Ohio is a microcosm of the debate over America's energy future. Coal still fuels 60 percent of the state's electricity (compared to 35 percent nationally) and the state also is a major oil refining and auto parts manufacturing center. It ranks fifth in the nation in carbon emissions.

Helping to drive coal's demise nationally has been abundant, cheap natural gas, an industry also now taking hold in in Ohio, with production from the state's Utica Shale up 12-fold since 2011.

Ohio has emerged as a leader in clean energy manufacturing; factories that once produced glass and appliances have been retooled to make renewable energy parts. Even though Ohio still only gets 2 percent of its power from renewable sources, it is now the nation's No. 1 manufacturer of wind turbine components, and the No. 2 maker of solar panel parts.

Strickland pushed for this transition when he served as governor from 2007 to 2011.

The son of a steelworker and native of the state's Appalachian coal region, Strickland set out to win support for renewable energy and energy efficiency mandates in parts of the state that were still dependent on coal. The plan, passed unanimously by the state's Republican-controlled Senate in 2007, required utilities to obtain 25 percent of their electricity from alternative energy sources by 2026.

But Ohio's renewable energy plan never had a chance to take off. The 2008 financial crisis and subsequent recession hit Ohio particularly hard and opponents of the renewable energy standards pushed a bill that rolled them back. It was sponsored by an Ohio state legislator who is on the board of the American Legislative Exchange Council. ALEC, a conservative group affiliated with the Kochs, has said it is working to repeal the mandates in states across the nation. The bill passed in 2014, making Ohio the first state to roll back its renewable energy standards.

The attacks on Strickland have resonated in a state where economic insecurity is high, even though unemployment has fallen to 4.7 percent, close to the national average. Inflation-adjusted wages have fallen in the state while rising nationwide, and labor force participation is at a 30-year low, especially among working age men.

Strickland has tried to remind voters of his roots in coal country and his record in Congress defending coal worker black lung benefits. But Portman won over miners in part by backing a bill this year to preserve the health and retirement benefits of workers for bankrupt coal companies—support that may only be symbolic, since the measure faces opposition from the Republican leadership.

Even more striking than Strickland's loss of union support is the collapse of support from the energy industry. During his last run for governor, he counted Duke Energy and FirstEnergy as campaign donors. Neither has given to his Senate campaign.

Oil, natural gas and coal PACs, along with individuals who work in those industries, have given Portman 97 percent of their total donations in this race—$300,000 compared to $9,000 to Strickland.

Fossil fuel donors, of course, are not the only interests that have made the Ohio Senate race one of the most expensive contests ever. A new Super PAC called Fighting for Ohio Fund, funded by hedge fund billionaires who are activists for conservative causes, has spent $9.7 million against Strickland, nearly as much as Freedom Partners.

Portman Has Backed Climate Action

Portman positions himself as a moderate on many issues, including carbon emissions. He was one of only five Republican senators who crossed the aisle last year to vote in favor of an unsuccessful budget amendment sponsored by Sen. Bernie Sanders (I-Vt.) that called for Congress to act on global warming.

But environmentalists say that Portman votes against action on climate change when it matters. He earned status as one of the League of Conservation Voters' "dirty dozen" candidates this year with his 8 percent score on environmental issues in this session, including his vote to block the Obama administration's Clean Power Plan.

Heather Taylor-Miesle, executive director of the Ohio Environment Council, said it is jarring to see fierce anti-regulatory groups as Portman's biggest supporters because he has backed government action on clean water and Great Lakes protection.

But on climate change, Taylor-Miesle said, Portman has been careful not to cross the fossil fuel industry.

"He criticizes Ted Strickland wrongly on coal jobs, and he is completely silent on the legislature actually taking steps to stall this big, growing clean energy industry in the state," she said. "Here's somebody who's had every opportunity in the world to lead on clean energy. And he continues, at best, to just tip-toe around this issue."