Marc Holtzman, the 25-year-old wunderkind who has gone from self-described "errand boy" for the powerful to candidate for the House of Representatives, recently filed a financial-disclosure statement providing new insight into the world of money in the nation's capital.

Holtzman is seeking to reverse the traditional route of winning office and then, in defeat or retirement, capitalizing on experience to become a high-dollar lobbyist.

Last year, at age 24, Holtzman parlayed his ties to key persons in and out of the Reagan administration, and his knowledge of the Pennsylvania political and business community, into a consulting/lobbying operation that grossed $380,000, according to his disclosure statement.

This year, he has started a campaign to win a House seat in a depressed northeastern Pennsylvania district, challenging first-term Democrat Paul E. Kanjorski.

As a candidate, Holtzman repeatedly has told his Horatio Algerpolitical success story.

It begins with a letter that he wrote to Ronald Reagan in 1976 at age 16 and includes running Reagan's Pennsylvania campaign in 1980 and rooming briefly in 1981 with Edwin Meese III, now attorney general, and Drew Lewis, later transportation secretary.

It also includes his tenure as chief of staff from 1981 to 1982 for Pennsylvania Lt. Gov. William Scranton and his service as executive director of Citizens for America, a pro-Reagan "grass-roots" lobbying organization, from 1983 through November 1984.

"I'm always trying to take maximum advantage of opportunities when they exist. I always try to make two plus two equal more than four," Holtzman said. "People, quite frankly, are always underestimating me."

That Holtzman is politically ambitious comes as no surprise to those who know him. His decision to run in Pennsylvania's 11th District, where his father's direct-mail sales company, Jewelcor, is a major employer, is widely seen as a logical, if tenuous, gamble.

Several of those who have come to know Holtzman expressed surprise at his ability to make a buck.

"I'm not a great genius who is going to reinvent the wheel," Holtzman admitted, "but I'm a good person at taking other peoples' ideas and making them happen, and figuring out how to get a square peg into a round hole."

Holtzman was best known for running Citizens for America, financed largely by $25,000 contributions from major Republican donors. The organization attempted to build support for administration policies that ranged from tax overhaul to aid for Nicaraguan counterrevolutionaries.

Although the organization paid Holtzman $79,913 last year, it ranked only second among his 14 clients. At the top was Phoenix Associates, which specialized in two very different areas: providing antiterrorist advice and training to international corporations and foreign countries, and "packaging" developers' grant applications to the Department of Housing and Urban Development.

Phoenix paid Holtzman & Associates $85,812 in 1984, all for steering clients to the company.

"I made some contacts for them Phoenix ," Holtzman said, explaining: "I'm always looking for opportunity. I was ultimately successful in facilitating some contacts for them that ultimately led to their security division doing some work."

In the case of the HUD contracts, he added: "I was helpful to them in a number of cases in making contact with successful businesses and developers that had no idea how to approach things in Washington or what programs were available . . . .I would simply make contact for Phoenix."

With the exception of the Citizens for America, almost all of the money that Holtzman made last year came from "making contacts." For example:

*For the National Coalition for Lower Prices, a organization of cut-rate retail stores and distributors, including his father's firm, Holtzman "would make contacts . . . .advise them who to talk to, help them see the people ultimately deciding their fate." The coalition paid him $24,058.

*For Data Access Systems, a firm that produced a computer system designed for political campaigns, he said, "I would simply make introductions for them with corporations and political clients." That paid $22,058. For Markdata, a Pennyslvaniadirect-mail firm, Holtzman said, "I made political introductions" to Washington direct-mail specialists. The increased business, he said, produced enough work to provide 150 new jobs in the district that he is seeking to represent. This paid his firm $43,021.

*For L.E. Lehrman & Co., owned by Lewis E. Lehrman for whom he worked at Citizens for America, "I did separate business and political consulting . . . not related to CFA. We had some joint investments together. We plotted political strategy, discussed issues." This paid $60,500.

Holtzman has made prominent friends, including former national security affairs adviser Richard V. Allen, Central Intelligence Agency Director William J. Casey and former U.N. ambassador Jeane J. Kirkpatrick. They have helped him collect a campaign war chest approaching $500,000, more than any other House challenger has raised.

At the same time he has, in his travels, stepped on toes. Some Republicans complained privately that they often felt that Holtzman was using them to make money, particularly in lining up "contacts" for his clients.

"Marc would call and say, 'Do me a favor and talk to someone.' I'd talk to the person and later find out Marc was getting a commission or something, just for lining up the call," said one person who often dealt with Holtzman.

Holtzman described basically this same process in discussing his work for Markdata: "A lot of time their salesmen would call and say, 'Hey, I would like to get in and see so and so on this committee.' I would make a phone call; the door would open. At that point, it was up to him to sell his product."

Among those who have expressed less enthusiasm about Holtzman's style are Michelle Laxalt, a prominent lobbyist and the daughter of Sen. Paul Laxalt (R-Nev.), and John Buckley, a scion of the conservative Buckley family, former deputy press secretary of the Reagan-Bush campaign and now press secretary to Rep. Jack Kemp (R-N.Y.).

Buckley, a former Lehrman aide who was forced out of Citizens for America by Holtzman when the organization was formed in 1983, declined to discuss Holtzman. Laxalt said simply: "I guess I'm forced to plead the Reagan-Laxalt 11th commandment and not speak ill of a fellow Republican."

Holtzman is undaunted by critics. In deciding to run for the House, he said: "I just said to myself, I'm a young guy, relatively successful, I've got a bright future . . . . I think some interesting people in corporate public life and other lives got their starts as errand boys."