When Rep. Richard A. Gephardt (D-Mo.) flew 42 House colleagues into Iowa last week to show off their support of him in Monday's presidential caucuses, a group of Washington lawyers and lobbyists went along for the ride.

Gephardt's Iowa campaign has surged since he added a sharp antiestablishment theme to his speeches and commercials.

But that did not stop his fund-raisers from inviting along such Washington insiders as a representative of ARCO, the oil company; the executive director of the American Dental Association political action committee, and a member of the Patton, Boggs & Blow law firm, one of the city's most notable lobbying groups.

Terence McAuliffe, the campaign's national finance chairman, said that the dozen extra passengers had helped raise money for Gephardt and that he made a pitch to them again on the way home.

McAuliffe said he hoped that a taste of actual campaigning "would get them excited so they would go out and raise more money."

Many of the members also wrote $550 checks to the campaign to help defray the charter's cost, approximately $15,000.

Several of the lawyers and lobbyists on the trip emphasized that they did so on their own time, not as representatives of their clients.

Figures supplied by the campaign show that Gephardt has received a larger percentage of his contributions from political action committees than any candidate of either party.

Sen. Robert J. Dole (R-Kan.), with $640,000, and Vice President Bush, with $540,000, have raised more, but Gephardt's $241,000 is about 8 percent of his total contributions, compared with Dole's 4.5 percent and Bush's 3 percent.

Meanwhile, in a bit of irony for Gephardt, who stepped to the front stage this week as a leader of opposition to contra aid, of the 47 Democrats who deserted their party to vote for additional aid on Wednesday, 22 are Gephardt supporters. Eleven traveled last week to Iowa with him.