A new super PAC has a different plan to take big money out of elections: Get candidates to sign a ‘no dark money’ pledge that would discourage money from anonymous sources.

The committee, CounterPAC, launched its first attack ads Tuesday in a Colorado House race. And while the committee doesn’t have the nationwide pool of donors of MayDay — another PAC that’s embracing the irony of raising big money to get money out of politics, it is making ripples through other means.

CounterPAC, funded by former Kongregate CEO Jim Greer and Google engineer Matt Cutts, is pushing federal candidates to accept a dark money armistice. Under the pledge, candidates that benefited from independent expenditures with undisclosed sources would agree to give 50 percent of the value of that expenditure to charity. Just how that agreement would be enforced is unclear.

CounterPAC’s staff said their approach was based on the DISCLOSE Act. It would still allow outside groups to accept million-dollar checks as long as they came from disclosed sources.

The PAC is targeting races in Alaska, Colorado, Georgia, Iowa and West Virginia. In West Virginia, where incumbent Democrat Nick Rahall is fighting to hold on to his Third District seat in an increasingly Republican state, Republican challenger Evan Jenkins has gone a step further — pushing the Rahall campaign to disavow all outside spending and PAC contributions.

So far, Rahall hasn’t budged. Incumbents tend to rake in heaps more PAC money than newcomers and the Democrat’s campaign has pulled in around $1.7 million from political committees, compared to Jenkins’ $200,000. Rahall’s refusal has given his opponent a new tool to bludgeon his opponent in press releases.

In Colorado, CounterPAC is doing some bludgeoning of its own.

On Tuesday the group went live with its first attack ad, a $120,000 expenditure slamming Rep. Mike Coffman, R-Colo. went. His opponent, Democrat Andrew Romanoff, agreed to sign the pledge if Coffman would follow suit.

See “Dark Money Mike,” below:

The ad suggests that Coffman is beholden to secret donors:

“Mike Coffman is enjoying the support of six-figure campaign ads funded by secret donors. The problem with secret donors is, you just don’t know who they are. Big tobacco? Russian oil billionaires? Too big to jail Wall Street bankers? The owner of China’s largest casino? We don’t know and that’s just how Mike Coffman wants it.”

Coffman’s campaign argues that the ad is in violation of the Colorado law prohibiting people from “recklessly” running false statements in ads meant to sway voters in an election. Lawyers representing the campaign sent a cease and desist letter to Denver’s KUSA, a local NBC affiliate running the ad:

“Mike Coffman has not received support from these sources and, as CounterPAC is well aware, their claim of “support” is not even possible because it is prohibited by federal law. The Federal Election Campaign Act (FECA) “prohibits any foreign national from contributing, donating or spending funds in connection with any federal, state, or local election in the United States, either directly or indirectly.” … Therefore, CounterPAC’s advertisement is patently false.

Knowingly or recklessly broadcasting political advertisements that include false statements would be a criminal violation under Colorado law …”

Outside groups like political nonprofits and super PACs are prohibited from coordinating with campaigns.

CounterPAC’s Campaign Director Jay Costa said the group is open to brokering agreements about what exactly constitutes adequate disclosure, but operates on the baseline principle that “the public should know who is spending money to influence elections.”