Because of computerized mailing lists, Congress has been increasingly subjected to so-called grass-roots lobbying pressure in the past few years.

Basically that means that an organization, through computerized mailing lists, has contacted a large number of people urging them to write their members of Congress on an issue.

Peace and environmental groups started the process in a small way. But business, the latest entry into the field, has added size and sophistication and as a result has scored some impressive victories in the 95th Congress.

Defeat of a cargo preference bill, a bill to expand construction site picketing and a bill to establish a consumer protection agency have all been chalked up to business-generated mail overcoming the Democrats' two-thirds majority in the House.

"It seems beyond question that the major growth area of organization lobbying today is that done through grass-roots lobbying," Common Cause President David Cohen says, admitting at the same time that 70 percent of the money his group spends on lobbying is spent on that technique.

Andrew Feinstein of Ralph Nader's Congress Watch said that not only are coinsiderable money and effort spent on the mass-mailing campaigns but also that a "whole outside industry has developed to service these needs."

Feinstein cited Richard Viguerie, whose Virginia-based firm provides mailing lists for many conservative and right-wing groups and coalitions.

Though they are susceptible to the pressure, many members of Congress also find the mail generated by this technique an ittitant, and complain that it distorts the view from back home as much as it helps them discover their constituents' beliefs.

The next two days should determine whether house members want to do something about it. The house will debate today a bill to expand public disclosure of lobbying activities. The key issue is whether organizations that have to register under the bill must disclose their attempts to generate grass-roots pressure. The bill as drafted by the house Judiciary Committee does not cover grass-roots lobbying, but an attempt is to be made to add it on the floor.

Common Cause and Congress Watch say it is "essential" and that no bill would be complete without giving the public this information.

But a strange-bedfellow coalition of the left, the right, the American Civil Liberties Union and the Chamber of Commerce oppose it.

The ACLU argues that the Supreme Court ruled on a 1946 lobby disclosure law that only direct contacts of members by lobbyists could be regulated, and reporting grass-roots efforts would be unconstitutional.

The ACLU and members of the Black Caucus will also fight another floor attempt to require organizations that have to register to disclose their major contributors. They argue that this could have a chilling effect on contributions to, for instance, black or gay organizations, and would also be unconstitutional.

The bill is expectedto pass easily, largely because many lobbyists' groups say they think that the significantly modified Judiciary Committee version is the best they can get. "Members of Congress have imposed disclosure on themselves, they surearen't going to let us off the hook," one lobbyist said.

But many amendments are expected as organizations try to change portions affecting themselves. Nader's group, for instance, is expected to oppose attempts to include upaid volunteers in the registration requirements.

And law firms and consultants who do lobbying on a retainer basis are opposed to the portion that would require any company that pays them more than $2500 a quarter to register and report their expenditures and activities as lobbyists, though the retainers themselves don't have to report unless lobbying is their sole source of income. William Timmons, head of one of the largest retainer-lobbying groups, said many companies will simply drop their retainers rather than do the bookkeeping.