New Federal Election Commission filings show liberal Democrats are rolling in the dough after their super PACs raked in double what their conservative Republican counterparts did in the first half of 2013.

After reviewing FEC filings, the Center for Public Integrity found left-leaning super PACs combined to raise more than $40 million in the first half of 2013. Conservative groups raised only about $20 million.

In the first half of 2011, however, conservative super PACs outraised liberal rivals 4-1. The second half of 2011 was even better for the conservative super PACs, out-raising those on the left 7-to-1.

In 2013, the top six PACs that have raised the most money all align with Democratic candidates. Thirteen of the 20 super PACs that took in more than $2 million were also liberal-leaning.

The top super PAC overall? Americans for Responsible Solutions, a group lead by former Democratic Rep. Gabby Giffords and her husband to support stricter gun control.

Between January 1 and June 30, the ARS super PAC brought in more than $6.6 million. Donors included billionaire Mac Benioff, founder and CEO of, New York Mayor Michael Bloomberg and Texas law firm owners Steve and Amber Mostyn.

Other top fund raisers include the Democratic Governors Association Action and the Workers' Voice super PACs. These two, including liberal-leaning House Majority and Senate Majority PACs, have all taken in $3 million or more so far in 2013.