Nominating conventions have become trade shows for the political world and major entertainment venues for corporations. CNNfn's Louise Schiavone looks at who is picking up the tab. Play video (Real or Windows Media)

NEW YORK (CNN/Money) - Everyone knows cash and politics go hand in hand. But perhaps never in such an obvious way as the event sponsorship at the upcoming political conventions.

Ever since Congress severely limited gifts to members and banned unlimited donations to political parties, special interests have had to be resourceful.

And what better place than the political convention, where the real action will be off the convention floor and behind the scenes at a couple hundred parties bought and paid for with corporate and special interest dollars.

For their convention in Boston next week, Democrats raised over $40 million from benefactors including Blue Cross Blue Shield of Massachusetts, Fidelity Investment Bank, Bank of America, AT&T, Fannie Mae, Coca Cola, Senator Kennedy, and the Heinz Foundation, run by John Kerry's wife Teresa Heinz-Kerry.

The private sponsorship has some concerned.

"You have parties going on all the time. You have members, when they are thrown in their honor in effect hosting their own huge expensive events, and you have corporations and special interests picking up the tab and getting the favoritism and the relationship with the members of Congress as a result," said Fred Wertheimer, president of the political watchdog group Democracy 21.

But not everyone sees the corporate cash as a black mark on the American political system.

Larry Moulter, a Boston business consultant, said the money would have to come from somewhere and better the corporations than the taxpayers.

"I just think we've become immune to it for the past 30 or 40 years," said Moulter. "Corporate America has put its fingerprints all over entertainment, sports and now politics."  

Reported by CNNfn's Louise Schiavone.