Still, weeks before the convention, Jones was confident that all costs would be covered by private contributions and corporation gifts. The committee isn't subject to federal restrictions on donations to candidates or parties and can accept unlimited sums from anywhere except foreign companies. Even then, U.S. subsidiaries of foreign corporations can contribute.
Democrats and Republicans also received about $18 million each in taxpayer money to stage their conventions, paid for by the voluntary $3 check-off on income-tax forms that underwrites the federal public financing system. And there's also a $50 million federal grant to cover security costs. In 2008, Democrats raised $55 million in private funding and Republicans raised $57 million on top of $16.4 million in public funding, Federal Election Commission records show.
Service-oriented companies such as Coca-Cola Co., AT&T Inc., Microsoft Corp. and United Parcel Service of America Inc. continue to view the conventions as powerful branding opportunities and are serving as official sponsors of the gathering in Tampa.
"Some companies get mileage out of this in terms of corporate branding," Jones says. "They want to look good on the world stage in front of more than 15,000 members of the media. This is not about politics."
Lobbyists for several of those companies insisted they were heading south for marketing purposes, not to influence the political conversation.
"My advice is go to a convention if you want to go to a convention . . . if you want to be a witness to this quadrennial political event," says Scott Segal, a lobbyist at Bracewell & Giuliani. "Don't go if you're thinking of doing business in any appreciable way."
Coca-Cola plans to send at least three lobbyists from its Washington office, as well as several state-based lobbyists, to both conventions. The company also has made a financial commitment to the Democratic convention through an affiliate of the host committee, New American City Inc., that decided to accept corporate contributions earlier this year.
Other companies made their commitments and planned their convention budgets a year or more ago and were reluctant to make last-minute changes, lobbyists say.
In 2008, Citigroup contributed $350,000 to the Minneapolis-St. Paul host committee for the Republican convention and $250,000 to the Denver host committee for the Democratic gathering, according to FEC figures. This year, the bank wrote a modest check just to the Tampa committee. Citigroup declined to discuss its contribution.
Biotech giant Amgen Inc. gave the Tampa committee $250,000. In Charlotte, Amgen is supporting health care and innovation policy forums hosted by outside liberal and centrist groups, including Third Way and Business Forward.
The Tampa and Charlotte host committees aren't required to disclose their donors to the FEC until Dec. 15 - a source of frustration for government transparency advocates.
The watchdog group Public Citizen submitted Freedom of Information Act requests to the mayors of Tampa and Charlotte as well as to the governors of Florida and North Carolina, requesting the release of a donor list before Oct. 15. Those requests were denied.
The host committees function much like a political campaign, raising money up to the start of the event. As of early August, Jones estimated that less than half of the money came from in-state donors and that the split between individual and corporate donors was about even.
Sen. Jeff Flake, R-Ariz., takes a selfie with his cut-out head during the Hoops for Youth 16th annual charity basketball game held at George Washington University's Smith Center, September 8, 2014. The members of Congress team beat the lobbyist team 46-40. Buy photo here.