Forget lobbying. When Washington, D.C.’s biggest trade associations want to wield influence, they often put far more of their money into advertising and public relations, according to a new Center for Public Integrity investigation.

Take, for example, the American Petroleum Institute. The oil and gas industry trade group spent more than $7 million lobbying federal officials in 2012. But that sum was dwarfed by the $85.5 million it paid to four public relations and advertising firms to, in effect, lobby the American public — including $51.9 million just to global PR giant Edelman.

From 2008 through 2012, annual tax filings show, the API paid Edelman a staggering $327.4 million for advertising and public relations services, more than any other contractor. 

It’s been well-publicized how much industry spends on lobbying the government, but little is known about how much money goes toward influencing the public. In an effort to find out more, Center for Public Integrity reporters examined the tax returns for trade associations that spent more than $1 million on lobbying in 2012. The IRS requires the groups to report their top five contractors.

Of $3.4 billion in contracts reported by the 144 trade groups from 2008 through 2012, more than $1.2 billion, or 37 percent, went toward advertising, public relations and marketing services, more than any other category. The second-highest total, $682.2 million, or 20 percent of the total, was directed toward legal, lobbying and government affairs.

By industry sector, the biggest clients of PR, marketing and ad services were energy and natural resources associations.The public relations industry is on a growth tear while the number of federally registered lobbyists is actually shrinking. Public relations work, unlike lobbying, is not subject to federal disclosure rules, and PR and advertising campaigns can potentially influence a broader group of people. In addition to Edelman, among the other major players are President Barack Obama’s go-to ad agency GMMB, “issue-advocacy” firm Goddard Gunster and government policy specialists Apco Worldwide.

While not a complete accounting of spending, the analysis provides a glimpse into just how important the public relations industry is to groups seeking to influence public policy.

Read the full report at the Center for Public Integrity