In the penultimate week before Election Day, conservative outside groups once again flooded the airwaves with attacks on Democratic candidates. Ten conservative groups were responsible for the 31 televisions ads we fact-checked – 16 of them targeting House candidates, 10 aimed at Senate candidates, and five attacking President Obama or cheerleading for Mitt Romney. As they did last week, Karl Rove’s American Crossroads and Crossroads GPS led the way, accounting for 12 of the ads we debunked. Since Monday, the two groups have announced four separate ad buys totaling a whopping $22.8 million.

Aside from American Crossroads and Crossroads GPS, several groups contributed to the assault on President Obama and Democratic Senate candidates. Restore Our Future, 60 Plus, and the American Future Fund each weighed in on the presidential race. We also fact-checked two Senate ads from the U.S. Chamber of Commerce and one apiece from American Commitment and Hardworking Americans Committee.

Coleman Groups Drill House Candidates With Oil-Funded Ads

But the most prolific groups focused on the House, where, in addition to four spots from Crossroads GPS, we answered five ads from the Congressional Leadership Fund, four from American Action Network, and three from Grover Norquist’s Americans for Tax Reform. Former Minnesota senator Norm Coleman is the chairman of both CLF, a super PAC, and AAN, a nonprofit that does not disclose its donors. CLF’s top individual contributors are billionaire Romney boosters Sheldon Adelson and Bob Perry, but it also recently received $2.5 million from Chevron – the “largest contribution from a publicly traded corporation” since the Citizens United decision – which is a good indication of who Big Oil expects to prioritize its interests in the next Congress.

Read more after the jump.