Organizations in the United States that engage in Advocacy Attempt to influence public opinion concerning: number in the thousands. There are many in each state, including new and fully-established groups. There are currently 35 subcategories of Advocacy Attempt to influence public opinion concerning: as defined by the IRS activities codes. These subcategories include everything from Anticommunism to Zoning or rezoning. Explore the links below to see what these organizations have to offer.