Fredreka Schouten of USA Today points to a significant loophole in the recent ethics bill passed by Congress: lobbyists can still underwrite the party national conventions, a big way to buy influence. Bills are in the works that might address this activity.
Fred Wertheimer of Democracy 21 knows that this underwriting is "a way in which these interests can buy undue influence," without abiding by the limits and disclosure requirements that govern campaign contributions.
Big parties and glad-handing with powerful elected officials characterize the conventions, as Schouten writes - a perfect venue to exploit financial investment for a little extra favor when it comes time to write legislation. Of course the corporations that cut checks to fund conventions deny it gets them anything - successful businesses are of course known for throwing money away on investments that get zero return.