This is actually a really tricky question. In short, no, there is no Democratic version of American Crossroads.As to why though... now that's an answer that's fun to explore. First off, let's go back to April 2010. American Crossroads gets its first mentions as Karl Rove pledges to spend $50M in the 2010 election cycle. (See: http://www.alternet.org/news/146...) The first thread to consider based on this initial framing is the collapse of the RNC as the national clearinghouse for Republican funding, due to Michael Steele and his radioactive reputation among reputable Republicans. These power brokers are seeking to punish Mr. Steele for his poor handling of the RNC. During the 2009 cycle, the largest beneficiary was the RGA, the Republican Governors' Association, headed by potential 2012 Presidential candidate Haley Barbour. In particular, the Republican candidates in NJ and VA benefited heavily from RGA money.After Rove announced the existence of American Crossroads, he quickly followed up by saying that he had raised $30M in pledges (see: Ibid.). This signaled a viable vehicle to deliver political funding aside from the official organizations, and with the advent of Citizens United allowing corporate sponsors to remain undisclosed, the money came pouring in.As a background, the Citizens United case (see: http://en.wikipedia.org/wiki/Cit..., http://www.seeingtheforest.com/a...), as Wikipedia puts it, was "a landmark decision by the United States Supreme Court holding that corporate funding of independent political broadcasts in candidate elections cannot be limited under the First Amendment." Political Action Committees, or PACs, became much more appealing when donating corporate money into elections.One major source of this funding is from health insurers, banks, and other financial institutes. Another source is groups like energy conglomerates and large non-unionized corporations like Wal-Mart. For the former, they are already affected by large Democratic initiatives, like the health insurance and financial regulations reforms. They seek to defeat Democrats to repeal or defund these reforms and return to the status quo. For the latter, the threat of the cost of bills like Cap-and-Trade and the Employee Free Choice Act are worth funding the defeat of Democrats to prevent these bills from becoming reality. As a result of Citizens United and the antipathy of various sectors of the corporate world towards Democrats, American Crossroads was able to access streams of cash to influence the coming elections.That's the long answer about why American Crossroads exists the way it does. To explain why the Democrats don't have an equivalent, I'll check off the various points in reverse.First and foremost, the DNC and the associated Democratic election organizations have been quietly effective this cycle, repeatedly out-raising their Republican equivalents most months, with the notable exception being the DGA, due to the previous mention of the RGA's success in directing funding from the RNC to itself.Second, as perception of the likely Republican wave has built, large Democratic donors are looking at the sunk cost fallacy and deciding not to ante up in the end game. (see: http://www.politicsdaily.com/201...)Third, the Democrats have positioned themselves as 'for the people' against 'Big Business,' and now that corporate money has been unrestricted for use in political campaigns, there really aren't many organized sectors of business to defend the Democrats. Instead, Dems are left to rely on their usual union support, which can now easily be matched and exceeded by corporate cash.That's my explanation for the success of American Crossroads and the lack of an equivalent on the Democratic side of the aisle.Update: Looks like Politico is also interested in this quesiton: http://www.politico.com/news/sto... tl;dr version - Obama for America is the closest equivalent, and they demanded that Democratic money go through them rather than outside infrastructure, resulting in the dismantlement of any sort of direct American Crossroads equivalent.