House Democrats in tough races are being advised by Dem leaders to seize on new revelations about the U.S. Chamber of Commerce’s foreign fundraising to defend themselves against the Chamber’s ad onslaught — another sign of just how urgent it is for Dems to counter the massive ad spending disparity they’re up against.

A senior Democratic strategist tells me that embattled incumbents and candidates are being instructed to seize on yesterday’s Think Progress report, which raised questions as to whether the money the Chamber raises from foreign companies is being used to help bankroll its multimillion-dollar campaign against Democrats.

House Dems and candidates who are being bludgeoned by Chamber ads will start raising the specter of foreign money rigging our elections as a way to fight back against the ads.

“Every single House Democrat being attacked by the Chamber of Commerce should use this extraordinary revelation to their benefit,” one strategist involved in charting House race strategy tells me.

“It makes a huge difference to people on Main Street if they know the Chamber ads are bought and paid for by Foreign owned companies that want to export American jobs,” the strategist continues. “Our guys need to go for the jugular on this and this news offers them a pretty sharp knife.”

One embattled Dem, Rep. Tom Perriello of Virginia, has already hit back against Chamber ads set to run in his district, describing them as un-American. “This latest move is beyond outrageous, to being fundamentally un-American and un-democratic, I’m just outraged,” he told a local news outlet, calling on his Republican opponent to renounce the Chamber’s ads. More will follow.

Separately, Sam Stein reports that similar tactics are already being used by Dem Senate candidates.

The Chamber has adamantly denied that any money raised from foreign companies is being used to fund ads here, claiming to have a process in place to prevent this. But there’s no way of verifying whether this is the case, and the Chamber has aggressively fought Congressional efforts to force the kind of disclosure that would shed light on such activities. And as many others have already pointed out, money is “fungible.”

The new campaign by Dems, which smacks of an effort to make lemons into lemonade, is another measure of the massive disadvantage Dems face in the uncharted post-Citizens United world. And it remains to be seen how much concerted efforts to raise questions about insidious foreign influence over our elections will do to counter the right’s massive edge.

UPDATE, 2:17 p.m.: Only Perriello has used the word “un-American” thus far; I’ve edited the hed to reflect that.