They do not seem the most likely classical music patrons: Northrop Grumman, General Dynamics, Boeing and Lockheed Martin. But together, these defense contractors are donating hundreds of thousands of dollars to the symphony orchestra in Johnstown, Pa., underwriting performances of Mozart and Wagner in this struggling former steel town. A defense lobbying firm, the PMA Group, even sprang for a champagne reception at the symphony's opera festival last month. Company representatives say they are being generous corporate citizens. But the orchestra is also a beloved charity of Representative John P. Murtha, Democrat of Pennsylvania, whose Congressional committee hands out lucrative defense contracts, and whose wife, Joyce, is a major booster of the symphony. For the first time, corporations and their lobbyists are being required to disclose donations they make to the favorite causes of House and Senate members, and a review of thousands of pages of records shows the extent - and lavishness - of this once hidden practice. During the first six months of 2008, lobbyists, corporations and interest groups gave approximately $13 million to charities and nonprofit organizations in honor of more than 200 members of the House and Senate. The donations came from firms with numerous interests before the Congress, such as Wal-Mart, the Ford Motor Company, Kraft Foods and Pfizer, and were received by charities ... as well as local groups controlled by members of Congress or those close to them.