Being openly identified as a donor carries certain risks. The advent of social media and hand-held cameras has upped the ante, allowing campaign operatives and trackers from groups like American Bridge 21st Century to capture and share instantly video of lawmakers hobnobbing with lobbyists.
"For a lot of companies, if you're on the host committee, it probably means the Obama guys have a hold of it, and who knows the way they operate?" another Republican consultant says.
Some companies have chosen to stick to informal engagements, sending their lobbyists but avoiding the publicity that comes with major contributions or flashy parties.
General Motors, for example, gave $200,000 to each party's host committee in 2008 and sent 735 cars to the two events combined, according to data compiled by the Campaign Finance Institute. This year, the automaker, still struggling after receiving billions of dollars in a government bailout, is sending only four lobbyists, a spokeswoman said.
It's a similar story for companies slammed by the 2008 market meltdown. "The financial services industry - like many industries - has become more cognizant of the bottom line," says one lobbyist for banks. "That's why folks are really scrounging around to get folks to come down."
Defense contractors also are loath to rack up extra expenses with the prospect of $55 billion in automatic cuts to the Pentagon budget early next year. Many companies are focusing on protecting themselves from the cuts.
"They are all looking to cut costs across the board," says one Republican defense lobbyist who is not attending his party's convention. "They are not even attending some key trade shows, so they are even more reluctant to spend resources on the conventions."
The changed landscape might make it harder for corporations to justify spending on future political gatherings, unless they can show the access has a bottom-line impact, according to lobbyists and other political players.
"It's the criminalization of engagement," says the Republican lobbyist close to Romney's campaign. "The optics are so bad that you're better off not going. ... If your goal to influence the political process and be part of it, don't bother."
Former Sen. Scott Brown, R-Mass., candidate for U.S. Senate in New Hampshire, holds his hand over his heart during the singing of the national anthem as he waits to take the stage for his town hall campaign rally with Sen. John McCain at the Pinkerton Academy in Derry, N.H., on Monday, Aug. 18, 2014.