Priorities USA Action, a Democratic so-called “super-PAC,” launched ads on Wednesday meant to counteract new ads by a conservative counterpart.

The ads, which will air for two weeks in a series of swing states, directly respond to the $20 million ad campaign launched this week by American Crossroads, the conservative super-PAC with ties to Karl Rove.

{mosads}Priorities USA calls the Crossroads ads “politics at its worst,” and accuses Republicans of wanting to end Medicare, slash education and give away tax breaks to oil companies and the wealthy.

It’s part of the developing rivalry between the two groups. Priorities USA’s buy is much smaller, just $750,000, and airing in Iowa, North Carolina, Virginia, Florida and Colorado. Bur Priorities USA has started to position itself as the best counterweight to Crossroads, which spent millions, fueled by unlimited and anonymous donors, on influencing the 2010 elections.

The Democratic National Committee also sought to respond to the Crossroads ads with a new Web video on Wednesday, but it is ultimately constrained in ways that Priorities USA isn’t.