If numbers are to be trusted, longtime advertising lobbyist Jim Davidson of Polsinelli Shughart is the top dog of the 2009 health care reform battle. Davidson’s name shows up 88 times, more than any other lobbyist, in a Center for Public Integrity database of health reform lobbyists compiled from U.S. Senate lobby disclosure records.

But, as is often the case when trying to nail down influence peddling in Washington, Davidson’s records are both accurate — and misleading. Davidson comes out first, because unlike other lobbyists, he did not take advantage of a loophole shielding individual company names from disclosure when lobby dollars are channeled through nonprofit associations. The case illustrates the complexity of tracking money spent by industry to protect its interests on the Hill.

Since the late 1980s, Davidson has been an advertising industry point man fighting restrictions on food advertising aimed at children, and battling calls to tax pharmaceutical companies’ advertising expenses.

Neither issue made it beyond the discussion stages in the 2009 health reform legislation, but Davidson monitored the legislation for media companies and manufacturers such as cable giant Viacom Inc., CBS Corp., drug group PhRMA, General Mills Inc. and the Grocery Manufacturers Association.

“What you find in any bill is that people will offer amendments that will try to undermine advertising,” Davidson said. “That’s why we find ourselves reported [in the Senate lobby disclosure documents] on a number of different issues.”

Federal lobbyists are required to file quarterly disclosure statements, but the true number they represent is many times higher than official reports, said James Thurber, director of the Center for Congressional and Presidential Studies at American University. Companies, organizations and individuals can remain invisible, for example, by funneling money to advocacy and professional associations that lobby on their behalf but are not required to disclose funders.

Davidson became king of the health reform lobby, according to the Center’s data, by overlooking this loophole. In addition to lobbying for clients at Polsinelli, Davidson is also the president of Alliance for American Advertising, a nonprofit association. The alliance, which is housed at Polsinelli, is little more than a sparse website and a conduit for gathering and spending advocacy cash.

The alliance filed lobby disclosures for each of the corporations and advertising groups that paid it to lobby on health reform. As a result, Davidson shot to the top of the health reform lobby data compiled by the Center. The nonprofit pools money from members and pays Polsinelli for him to lobby on their behalf. “It’s just less paperwork,” Davidson said.

The arrangement is common and legal, said Craig Holman of the Washington watchdog group Public Citizen. Lobby firms often set up nonprofits “to do certain things that they can’t do as a regular lobby firm,” like buying television ads and paying for advocacy work without revealing the individual interests that paid for them.

After the Center’s inquiry, Karen Blitz, who fills out lobby disclosure forms for the alliance and for Polsinelli, talked to an official at the Senate’s public records division and learned the alliance was filing more than the law required. In the future, she said she won’t error on the side of disclosure.

“I guess I should thank you,” Blitz said. “You saved me a lot of work.”