A coalition of Democratic-aligned outside groups seeking to influence races up and down the ballot in 2012 brought in a combined $10 million in the first six months of the year, according to those familiar with the fundraising totals.

“The overwhelming support we have received in getting each of our groups off the ground shows that Democrats won’t be sitting on the sidelines in 2012,” reads a joint statement released by the four groups.

The groups — Priorities USA Action, American Bridge 21st Century, Majority PAC and House Majority PAC — were formed earlier this year in an attempt to combat American Crossroads, a conservative outside organization that has pledged to spend $120 million in 2012 and has already spent better than $20 million on television ads.

Most of the Democratic groups are organized as so-called “super PACs” meaning they can accept unlimited donations but must disclose their contributors to the Federal Election Commission.

Priorities USA Action, which was started by former White House aides Bill Burton and Sean Sweeney and is expected to primarily focus on running ads in the 2012 presidential race, raised $3.16 million in the first six months of the year — the most of any of the Democratic-affiliated super PACs.

American Bridge, a research operation for presidential, Senate and House races , brought in $1.56 million. Majority PAC, which is aimed at keeping Democrats in control of the Senate, brought in $1.25 million while House Majority PAC, which is focused on the lower chamber, collected $985,000.

Priorities USA and American Bridge both have affiliated 501(c)(4) not-for-profit arms, which can raise unlimited sums and don’t have to report their donors but are limited in how much political activity they can do.

The Priorities USA 501(c)(4) collected over $2 million while the American Bridge 21st Century Foundation brought in roughly $1.5 million.

The early returns suggest the shadow Democratic party being built by party operatives will be sufficiently funded as major donors in both parties gear up for 2012.

Jonathan Collegio, a spokesman for Crossroads, said that his groups had a “two-to-one lead” over all of the groips combined. “We expect the left will eventully outspend us once the cash-rich unions kick into gear,” added Collegio.

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