The weekly meetings of the House's 223 Republican members in the Capitol basement are supposed to be sacrosanct: no lobbyists allowed. But last week GOP leaders broke their rule by letting a health care lobbyist brief them on her proposals for Medicare reform, and some congressmen privately protested after she failed to disclose her clients' enormous financial stake in the issue.

The controversy over lobbyist Deborah Steelman's speech to the House Republican Conference dramatizes the dangers that arise when a Washington player takes on a variety of roles on different stages, and forgets to switch hats from one audience to the next.

At the same time that Steelman is a top hospital and pharmaceutical industry lobbyist, she also is a leading health care policy expert who served on a key Medicare commission, as well as a GOP donor, a party political operative and a top domestic policy adviser to Texas Gov. George W. Bush in his presidential bid.

Steelman agrees she should have disclosed her clients' interests at the GOP gathering last Wednesday. But she added that in her mind, she was addressing the group not to promote any client's agenda, but solely as a Republican activist and member of the recent Medicare reform panel chaired by Sen. John Breaux (D-La.) and Rep. Bill Thomas (R-Calif.).

"To me, it was a policy hat session," she said. "I was doing my Republican health activist bit."

Even so, a Republican House member in attendance said several colleagues thought that given her clients' interests, having her speak was "dumb." A GOP strategist likened Steelman's address to "the NRA coming in and writing gun legislation, except with her there was no disclosure."

Steelman is paid approximately $2 million a year by health care clients, including pharmaceutical firms such as Bristol-Myers Squibb, Pfizer and Johnson & Johnson, and industry associations such as the Healthcare Leadership Council. While some of her clients agree with her recommendations to the conference -- which concerned how to fund drug prescription insurance for the 13 million elderly people who lack that coverage -- others of her clients disagree, industry officials said.

She's widely known in GOP circles for her passion in promoting her ideas, which also were endorsed by 10 of the Breaux panel's 17 members. They advocate a set of complex Medicare reforms, such as having elderly people who are not poor pay for prescription drugs themselves, with no government subsidies, and allowing patients to choose private health plans. President Clinton criticized the panel's proposals and Democrats, with an eye on the coming elections, are raising the issue of drug coverage for the elderly in a way Steelman thinks is opportunistic.

Steelman contends Republicans should exploit the Medicare issue to win over moderates and women -- an idea greeted with skepticism by many GOP leaders. Eager to lay out her ideas, Steelman accepted an invitation by conference Chairman J.C. Watts (R-Okla.) to give the speech. But some other senior GOP House members advised her not to give the address, fearing her role as a lobbyist would spark criticism that the party is letting industry call the shots on legislation.

At a GOP fund-raising dinner days before the event, Steelman had a loud argument with some congressmen who expressed such concerns. According to a person who witnessed the argument, one congressman told Steelman, "The conference is at risk, because we have lobbyists briefing us." To which Steelman reportedly replied: "I'm not doing a client pitch. . . . I don't want to lose the opportunity to address this group."

Steelman said she intended to disclose her lobbying interest at the hour-long gathering, but became disconcerted by the scattered nature of the discussion and forgot to mention it.

Conference officials said her appearance didn't stoke controversy. "This is a very complex issue, and she's a top talent," said conference spokesman Lauren Maddox. "She didn't speak about specific legislation, and members were pleased to hear from her."

In the past, critics have said that Steelman was inattentive to the boundaries between the lobbying, political and policy realms she inhabits. A top health care official in the Reagan White House, she chaired a Medicare panel in the Bush years, and consumer groups denounced her then for pushing ideas that industry favored. Earlier this year a consumer activist organization, Public Citizen, said she had a "major conflict of interest" for serving on the Breaux commission as a lobbyist.

But Steelman said she is "scrupulous" in observing those boundaries. On the Breaux panel, she had clients sign letters saying she had told them she would not promote their views on the commission.

Steelman acknowledges that her passion for the issues on which she lobbies might confuse people about which of her portfolios she's carrying at any point. But she keeps them straight, she says.

"I've worn policy hats and client hats for so long," she said, "it's ingrained in me."

Staff writer Maralee Schwartz contributed to this report.