The Democratic opposition research shop American Bridge is launching a new web ad seeking to debunk attacks launched by a Koch brothers-backed outside group in a handful of competitive Senate races.

The web ad uses clips from MSNBC hosts Al Sharpton and Alex Wagner, as well as local news reports, to highlight criticism of and issues with ads run by Americans for Prosperity, a major GOP outside group funded in large part by the Koch brothers.

It highlights the fact that a number of AFP’s ads used paid actors, rather than real residents of the state they aired in, as well as independent fact-checkers debunking the claims in one ad.

It closes: “The Koch agenda: Good for them, bad for the middle class.”

The ad is running in Alaska, Arkansas, Colorado, Louisiana and Michigan.

AFP has poured more than $30 million since August into attack ads in competitive House and Senate races this cycle.

Democrats openly admit they expect to be outspent on air, but to combat the attacks they’re engaging in a protracted effort to undermine the credibility of the ads by highlighting inconsistencies and attacking the Koch brothers.