Republicans are counting on a deluge of money from the Koch brothers to help sweep them to victory this fall. But Democrats are looking to perform some political jiujitsu: by turning the controversial billionaires into weapons against the GOP.

Control of Congress for the next two years could depend on whether they succeed.

In tight House and Senate races from Colorado to West Virginia and from Iowa to New Hampshire, Democrats and their allies are seizing on the Kochs’ vast spending to tie GOP candidates to the brothers. Here’s a typical recent example from a press release sent out by the campaign of Colorado Democratic Sen. Mark Udall, who is being challenged by Republican Rep. Cory Gardner:

“The Koch Brothers and their dark money allies are coming to Congressman Gardner’s rescue because he relentlessly pursues their radical agenda to end Medicare as we’ve always known it, gut Social Security for our seniors, and support tax breaks for companies that ship American jobs overseas.” Several Democratic-leaning groups have extended the attack on Udall’s behalf. “Voters get the fact that if these two guys are going to spend hundreds of millions of dollars, they expect something in return.” Craig Varoga of Patriot Majority

The strategy of targeting the Kochs — a tactic pioneered by Senate Majority Leader Harry Reid, who has been hammering the pair all year — has had its share of critics, many of whom see attacking private citizens as below the belt, and ineffective to boot. The maneuver is borne in part out of necessity: Many Democrats have little else to run on since President Obama has low approval ratings, especially in the red states where many key Senate races are playing out, and Congress is largely sitting on its hands.

But lately there are signs that the strategy may be bearing fruit.

Craig Varoga, who runs the Democratic-aligned group Patriot Majority, has conducted public opinion research in about a dozen states on the impact of the anti-Koch message. He said the attacks resonate with voters in two distinct ways: By playing on concerns about the flood of dark money that’s threatening to overwhelm political campaigns, while also associating Republican candidates with the Kochs’ right-wing policy goals.

Close video The political reach of the Koch network Bill Scher from Campaign for America’s Future and Mother Jones’ Andy Kroll discuss the influence of the Koch brothers heading into the critically important midterm election. Bill Scher from Campaign for America’s Future and Mother Jones’ Andy Kroll discuss the influence of the Koch brothers heading into the critically important midterm election. share tweet email Embed

“This is not gut intuition,” Vargoa added. “This is data-driven.” Varoga did not share the data itself.

In that sense, then, attacking the Kochs isn’t really about the Kochs. It’s a way of creating human villains to dramatize the Democrats’ case that the Republican agenda would put the interests of wealthy and well-connected corporations ahead of ordinary Americans.

The Kochs have largely avoided responding to specific attacks by Democratic campaigns or allied groups. But representatives for Koch Industries, the privately held Kansas-based multi-billion dollar corporation owned by the brothers, have called the attacks by Reid “malicious” and “desperate,” and have accused the Majority Leader of “waging war on private citizens.”

Of course, the Kochs’ involvement in politics is still very likely a net positive for Republican candidates. Their sprawling network of nonprofit political groups is expected to spend a total of $290 million to elect conservatives this fall. Six Koch-tied groups have funded almost 44,000 ads in battleground states, a good-government group reported this month. The Koch groups are barred by campaign finance laws from legally coordinating with the campaigns, but are free to spend an unlimited amount supporting or attacking candidates based on the key issues in the race . “The Koch Brothers have become their own negative brand, and it’s beginning to permeate the psyche of voters.” Rep. Steve Israel

In two of the Senate races that could determine control of the chamber next year, North Carolina and Louisiana, the Kochs have been particularly helpful. Those states respectively have seen 8,600 and 6,900 Koch ads — many of which served to drive down the Democratic incumbents’ approval ratings earlier this year. At a recent Koch retreat, several top Republican candidates including Gardner, Iowa state Sen. Jodi Ernst, and Rep. Tom Cotton of Arkansas lauded the brothers and made barely veiled pleas for additional support.

Still, it’s not just Varoga who’s finding that Democrats may be on to something. A strategy memo summarizing recent polling for a group that has targeted Republican incumbents over climate change contained similar findings.

Close video Fundraisers take on the Koch brothers Must-Read Op-Eds: “David Brock…is part of a behind-the-scenes campaign to convince donors it’s OK to attack the Koch brothers for spending millions of dollars while doing the exact same thing for the left,” write Politico’s Kenneth Vogel and Tarini… share tweet email Embed

Lehane wrote that the dynamic is playing out in Senate races in Colorado, New Hampshire, Michigan, and Iowa, where 71% of likely voters said they’d be less likely to support a candidate if he or she was being bankrolled by the Kochs.

In a recent interview with msnbc, Rep. Steve Israel, who chairs the Democratic Congressional Campaign Committee, singled out a race in which Rep. Nick Rahall, a veteran West Virginia Democrat, faces a tough challenge from Republican Evan Jenkins. Democratic ads tying Jenkins to Koch-funded attacks on Rahall have given the incumbent a crucial boost, according to Israel.

“The Koch Brothers have become their own negative brand, and it’s beginning to permeate the psyche of voters,” Israel said.

Whether that pays dividends for Democrats come November remains to be seen.