Conservative groups and the Republican candidates they support continue to be the big winners from a surge in independent campaign contributions unleashed by the 2010 Citizens United decision, a new analysis of Federal Election Commission data shows.

Through the end of June, conservative-leaning groups dominated the top 15 so-called Super PACs , which can now take in unlimited amounts of campaign cash from individuals and corporations to spend on specific campaigns as long as they don’t coordinate with the candidates. They outraised their liberal counterparts by a three-to-one margin, according to data compiled by MapLight, a California-based watchdog group.

Topping the list was Restore Our Future, a Super PAC set up by Republican campaign operatives with close ties to presumptive nominee Mitt Romney. The group has raised $81.2 million, according to the latest filings, which is nearly four times the $20.9 million raised by Priorities USA, the group that is working to boost President Obama’s reelection bid.

American Crossroads , whose top advisors include Republican heavyweights Karl Rove and Haley Barbour, is the second leading money-raiser among Super PACs having raked in $40 million through the end of June. Winning Our Future, which early in the campaign boosted Newt Gingrich’s candidacy, ranked third with $23.3 million raised.

Candidate campaign fundraising shows a different story, with Obama raising twice as much as Romney, according to the Center for Responsive Politics. Obama has raised more than $300 million compared with $154 million for Romney.

Spending on all federal races this year – for the White House, House and Senate – is expected to reach $6 billion, a nearly 20 percent increase from four years ago. About 15 percent or nearly $1 billion will come from groups whose contributors are no longer bound by limits in the nation’s campaign finance laws, according to Sheila Krumholz, executive director of the Center for Responsive Politics.

And half of those contributions won’t be open to public scrutiny because they went to outside groups that, unlike the Super PACs, don’t have to disclose their donors unless they make “electioneering communications” within 60 days of the election. “The SuperPACs and outside groups will have a profound effect on this year’s election,” Krumholz said. “Most of what we can see is from conservative donors to conservative groups.”

Groups that don’t have to disclose their donors include Crossroads GPS, which also has links to Rove. It is run by Steven Law, whose previous jobs included general counsel of the U.S. Chamber of Commerce and chief of staff to Senate Minority Leader Mitch McConnell of Kentucky.

It’s likely that the biggest donors to the outside groups that don’t disclose their donors are similar to the ones that give to the Super PACs, Krumholz said. By far the biggest Super PAC giver was casino mogul Sheldon Adelstein and his wife Miriam, who donated nearly $40 million to groups pushing first Newt Gingrich’s candidacy, then Romney’s candidacy and the election of a Republican Congress.

Unions topped the list of liberal-leaning Super Pac contributors with the National Education Association giving $5.3 million, most of it to its own independent group, and the Service Employees International Union giving $3.7 million. Both organizations represent millions of public employees.

The Citizens United decision “affected our political system in such a way that it forces all aspects of the political spectrum to participate in it,” said Jeffrey Ernst Friedman, researcher director of MapLight.



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