Fredreka Schouten

USA TODAY

WASHINGTON — Charles Koch has insisted his conservative network won't wade into the presidential race to help Republican Donald Trump, but a new ad from Koch's main political group invokes Democrat Hillary Clinton to attack one of her party's contenders for the Senate.

The 30-second commercial from Freedom Partners Chamber of Commerce targets Ohio Democrat Ted Strickland and replays Clinton comments from a March town hall. Referring to a transition to clean energy, she told the audience at the CNN-hosted event: "We're going to put a lot of coal miners and coal companies out of business, right?"

In the ad, "Josh W.," a worker from Ohio's coal country wonders aloud whether he can trust Strickland to defend miners' jobs. "Seeing Ted Strickland stand with Hillary Clinton after what she said really hurts us here in the coal industry," he says.

The commercial, part of a $1 million ad buy in Ohio, marks the first time the Koch group has used Clinton's name in their advertising and foreshadows a strategy Republicans hope to use in the months ahead to undermine Clinton and other Democrats with working-class white men.

"As we have said before, we are not engaging in the presidential, however, showing how Ted Strickland has been a rubber stamp for Hillary Clinton’s job-killing agenda is the most relevant and impactful message in this state," Freedom Partners spokesman James Davis said in a statement about the ad's focus on Clinton.

Freedom Partners' has pumped nearly $10 million into the Ohio Senate race to attack Strickland, a former governor who wants to oust Republican Sen. Rob Portman. The latest Ohio buy includes a separate ad, attacking Strickland's record as governor.

The group also is spending $1.2 million in Nevada this week on TV and digital ads to target Democrat Catherine Cortez Masto, who is battling Republican Rep. Joe Heck for an open Senate seat now held by the Senate's top Democrat, Minority Leader Harry Reid.

Clinton's words about the coal industry have haunted her campaign in places such as West Virginia, a state she won in her 2008 primary against then-senator Barack Obama but lost this year to Vermont Sen. Bernie Sanders.

As the fact-checkers at Politifact note, she has sought to clean up the March comments. "It was a misstatement," she told a crowd in West Virginia earlier this year. 'What I was saying is the way things are going now, they will continue to lose jobs. It didn't mean that we were going to do it."

A Monmouth University poll released this week shows Clinton with a slight, four-point advantage over Trump in Ohio among likely voters, while Portman leads Strickland 48% to 40%.