The American Association of Retired Persons is No. 1 on FORTUNE's second annual ranking of the 25 lobbying groups with the most clout in Washington. AARP captured the top spot last year with the American Israel Public Affairs Committee taking second place for two years running. Completing the list of the top five interest groups are: National Federation of Independent Business (No. 3), National Rifle Association of America (No. 4) and AFL-CIO (No. 5). In the December 7 issue of FORTUNE, senior writer and Washington bureau chief Jeffrey H. Birnbaum identifies the Power 25 and reports on how the business of politics is played in and outside the Beltway.

This year's survey contains a second winners' roster - a rating of the leading lobbying firms and, by inference, the most politically potent individual lobbyists. Verner Liipfert Bernhard McPherson & Hand heads this list and boasts Bob Dole, George Mitchell and Lloyd Bentsen among the firm's heavyweights. Barbour Griffith & Rogers, Akin Gump Strauss Hauer & Feld, Patton Boggs, and Timmons & Co. round out the top five firms.

Polling for the Power 25 was conducted by the Mellman Group, a Democratic polling firm, and Public Opinion Strategies, a Republican outfit. This year's questionnaires asked respondents to assess the political clout of 50 specific lobbying companies and 75 trade associations, labor unions, and interest groups and to name the most powerful lobbying firms and lobbyists. The survey was sent to nearly 2,700 individuals, including every member of Congress, Hill staffers, senior White House aides, professional lobbyists and top-ranking officers of the lobbying groups and lobbying companies. Nineteen percent of the surveys were completed and returned.

"Washington lobbying isn't what you'd expect," writes Birnbaum. "The capital's mightiest lobbyists aren't shadowy creatures who shun the spotlight. Many are among the nation's best-known public servants who until recently were Sunday talk-show regulars, and in some cases still are."

The 1998 rankings provided a few surprises. The Credit Union National Association, representing the nation's 12,000 credit unions, jumped on the strength of its legislative rout of the banking industry this year to No. 8 from No. 70 and the National Beer Wholesalers Association moved up to No. 24 from last year's No. 34.

There was a lot of shuffling among organized labor on this year's list. The AFL-CIO, which dropped to No. 5 from No. 3 last year, and the National Education Association, which plummeted to No. 21 from No. 9, are the only two labor organizations remaining in the Power 25. Newcomers to the Power 25 list include three insurance groups - the Independent Insurance Agents of America (No. 12), the Health Insurance Association of America (No. 22), and the American Council of Life Insurance (No. 23).

The results of the survey would be vastly different if questionnaires were filled out only by people from one party or the other, reports Birnbaum. Unions, for example, poll well among Democrats. If only Democrats were surveyed, the United Auto Workers and the American Federation of State, County, and Municipal Employees would be a part of the Power 25. A Republican Power 25 would include such GOP stalwarts as Americans for Tax Reform, the National Retail Federation, and the American Legion.

In evaluating the who's who among powerful lobbyists, respondents drew the central conclusion that hand-to-hand lobbying is all about access, and the firms that have more of it rank higher than those with less. Size doesn't matter, writes Birnbaum. Verner Liipfert employs 185 lobbyists and lawyers while Barbour Griffith has just 13. Only four on FORTUNE's list of 10 most influential firms land among the 10 biggest in terms of lobbying revenue.

FORTUNE notes that, surprisingly, a fat campaign contribution kitty does not automatically translate into clout in Washington. Such powerhouses as the AARP (No. 1) and the Christian Coalition (No. 7) don't have political action committees (the main vehicles for distributing campaign contributions), while groups such as the National Automobile Dealers Association (No. 48) and the International Association of Machinists and Aerospace Workers (No. 73) ranked relatively low in the survey despite PAC's that brought in more than $3 million this election cycle