Two of the guests at an exclusive brunch Wednesday where Chicago Mayor Rahm Emanuel attempted to steer donors toward Priorities USA, the super PAC supporting President Barack Obama's reelection campaign, are seasoned campaign bankrollers — one of them with a past that leans Republican. 

A look at the campaign giving histories of New York investor Orin Kramer and Chartwell Hotels CEO George Tsunis, identified by the New York Times as having heard Emanuel's official debut as a pitchman for the super PAC, gives an example of the type of donors Democrats are targeting as they try to catch up with the cluster of super PACs backing Republican presidential nominee Mitt Romney. One sign of stepped-up urgency on the part of the president's party:  Emanuel, who served as Obama's first White House chief of staff, has just given up his honorary post at the Obama campaign to spearhead the drive for super PAC donations. Federal law prohibits super PACs from "coordinating" with candidate committees though the ban so far has been loosely interpreted, as Emanuel's past affiliations attest. 

Both Kramer and Tsunis have long donation histories and already made sizeable contributions to super PACs this cycle, Sunlight's campaign money trackers, Follow the Unlimited Money and Influence Explorer, reveal. 

Kramer, who currently manages Boston Provident LP, has a long history in Democratic politics, beginning in Carter's domestic policy staff. Since then, he has become a huge financial player, donating over $2 million since 1989 and serving as a national finance adviser for the 2004 presidential campaign of Sen. John Kerry, D-Mass.

This cycle, Kramer has donated $160,000 to super PACs and other committees, after maxing out to Obama Victory Fund early last year. He has given $15,000 to Priorities USA and $20,000 to House Majority PAC. And, according to the Times, he hosted a pool party for other Democratic moguls at the Ritz-Carlton in Charlotte where former Treasury Secretary Robert Rubin took an unintentional dive into the water. 

Tsunis, who lists Winston Churchill as "Mentor" on the personnel page of Chartwell — named after the fabled British prime minister's family home — has less of a past in Democratic politics. The real estate mogul has donated more than $1 million since 1992, but almost all of it in the last three election cycles. Of the $250,000 he gave in 2008, more than two-thirds went to Republicans, including that year's Republican presidential ticket, Sen. John McCain, R-Ariz., and former Alaska Gov. Sarah Palin.

Tsunis appears to have changed his loyalities in 2010, and since then has given largely to Democrats, with a few Republican outliers. 

His donations for 2012 total more than $300,000, mostly to committees. Like Kramer, Tsunis has given the recommended $35,800 to the Obama Victory Fund, and $60,000 went to DNC Services Corp. He is also one of the few people bankrolling the New Directions for America PAC, giving $125,000 of its total take of $345,000. So far New Directions' only contributions have been on behalf of Dan Roberti, who lost a Democratic congressional primary last month in Connecticut.