Freedom’s Watch, the conservative advocacy organization heavily funded by Las Vegas billionaire Sheldon Adelson, is hitting the airwaves with a television and radio ad buy targeting Democratic House candidates across the country.

It is Freedom Watch’s single largest advertising purchase since the organization aired ads earlier this year in a Mississippi special election, according to a source familiar with the buy. The size of the buy is in the mid-six figures.

The ads take aim at Democratic incumbents, challengers, and open seat candidates. Ads airing on broadcast television are targeting U.S. Rep. Nancy Boyda (D-Kan.) while ads on cable stations are taking aim at U.S. Rep. Nick Lampson (D-Texas).

Radio ads, meanwhile, are targeting Michigan 7th Congressional District candidate Mark Schauer, Ohio 15th Congressional District candidate Mary Jo Kilroy, Idaho 1st Congressional District Candidate Walt Minnick, Missouri 6th Congressional District candidate Kay Barnes, New York 29th Congressional District candidate Eric Massa, New Mexico 1st Congressional District candidate Martin Heinrich, Ohio 16th Congressional District candidate John Boccieri, U.S. Rep. Carol Shea-Porter (D-N.H.), U.S. Rep. Chris Carney (D-Pa.) and U.S. Rep. Don Cazayoux (D-La.).

“70 percent of Americans are in favor of exploring for offshore oil. But new Congressman Don Cazayoux has opposed efforts to increase domestic energy production 10 times. No wonder he’s endorsed by a liberal special interest group that favors high gas prices,” an announcer at the start of the 60-second spot targeting Cazayoux.

“Two years ago the Democrats said they had a plan to lower gas prices. But nothing’s been done,” the ad continues. “And Cazayoux? Instead of staying in Washington to fix the problem, he was the deciding vote to send the House on a five-week recess. In Washington, Cazayoux was beholden to Nancy Pelosi and the liberal DC special interests. But when he goes back home, he sings a different tune.”

Unlike some radio spots the organization has aired in the past, each of the new ads are crafted to apply to each individual district.

Democrats fired back against the ads. 

“National Republicans have spent years stuffing their pockets with Big Oil money and then thanking Big Oil by blocking Democratic efforts to lower gas prices and make America energy independent. So it’s not surprising that Republicans are outsourcing their false attacks to a shadowy soft money group like Freedom's Watch which won't even reveal whether Big Oil has joined casino magnate Sheldon Adelson in funding them," said Doug Thornell, a spokesman for the Democratic Congressional Campaign Committee.

That Freedom’s Watch is investing in House races is surely welcome news for the National Republican Congressional Committee. The beleaguered GOP House campaign arm trails its Democratic counterpart in fundraising by a steep seven-to-one ratio.