Two of Washington's top lobbying firms are among the major funders of a Super PAC formed to assist President Obama's re-election campaign, according to the Center for Public Integrity's Michael Beckel.

The PAC is Priorities Action USA, and Beckel found that "since it was launched in April 2011, Priorities USA Action has raised just $771,000 from businesses. That's about 5 percent of the $21 million that the super PAC has raised through the end of June. Two of these six donors to Priorities are firms specializing in government relations with offices in D.C., blocks from the White House."

Also prominent among Perennial's leadership is Stephanie Baucus, daughter-in-law of Senate Finance Committee Chairman Max Baucus, D-Mont.

The two include Perennial Strategy Group LLC and MWW. The former, which is based in the nation's capital, gave Priorities $600,000, while the latter, which is based in New Jersey but maintains a D.C. office, contributed $50,000.

"Records show Perennial's clients over the years have included Regions Financial Corp., Hewlett-Packard, the Avis Budget Group car rental company, the energy company Southern Co. and the MGM Mirage casino," according to Beckel.

"Perennial's founder and CEO Lamell McMorris, has donated the legal maximum of $5,000 to Obama's re-election campaign. McMorris, who is also on the national board of directors of the NAACP and is a former CEO of the Southern Christian Leadership Conference, has further given the legal maximum of $61,600 to the DNC during the past two years," Beckel said.

Also prominent among Perennial's leadership is Stephanie Baucus, daughter-in-law of Senate Finance Committee Chairman Max Baucus, D-Mont.

Among MWW's clients, according to Beckel, are "Blue Cross Blue Shield of Florida, Molycorp Minerals and several municipalities and universities."

Priorities USA has also received significant contributions from labor unions, including "the PACs of the Service Employees International Union ($1 million), the National Air Traffic Controllers Union ($1 million), the United Association of Journeymen and Apprentices of the Pipe Fitting Industry ($250,000), the United Auto Workers ($100,000) and the National Association of Social Workers ($5,000)," Beckel said.

In a related study, Beckel found two super PACS that are backing likely Republican presidential nominee Mitt Romney are predominantly supported by contributions from corporations and businesses.

"The top two super PACs -- the pro-Mitt Romney Restore Our Future and Karl Rove's American Crossroads -- have raised nearly $24 million in contributions from companies so far this election cycle, a Center for Public Integrity analysis has found. Donors include hedge funds, energy companies, dietary supplement makers and even a popcorn manufacturer," Beckel said.

"The list includes a handful of Fortune 500 and other publicly traded corporations, but donors are more likely to be privately held businesses, often organized as limited partnerships or limited liability companies," he said.

For more from Beckel on the Romney supporters, go here. And click here for the unions.