WHO IS TRYING to influence Congress? The latest reports by lobbying groups filled about 100 pages of small print in last Friday's Congressional Record -- and still covered only a fraction of the lobbying that occurs on Capitol Hill. House and Senate committees are about to try for the umpteenth time to compose a more adequate disclosure law. But once again the advocates of "full disclosure," pushed by Common Cause, are asking for too much. They are not content with a statute requiring reports on substantial paid (as opposed to volunteer) lobbying that involves direct contacts with members of Congress and their staffs. A "strong" disclosure bill, they insist, should also cover so-called grass-roots or indirect lobbying -- efforts to influence Congress by Stimulating letters and other appeals from people back home.

Such attempts to stir up public opinion have become very popular. Thousands of organizations use sophisticated mass mailings to try to generate pressure on Congress. Many companies routinely urge their stockholders to write about one concern or another. Labor unions mobilize mail from their members frequently. Reports about all this and its financing would make interesting reading. But required disclosure is not really necessary. Most of these campaigns are already quite visible; groups often brag about how many post cards they can generate, and any member of Congress who is not totally out of touch with his constituents can find out very quickly who is behind any surge of similar appeals.

Beyond that is the fact that mandatory disclosure would be just that -- the injection of federal law into a field of political activity that is entirely legitimate and extremely widespread. And requirements for reporting would be just the start of it; there would also be provisions for audits and inspections of groups' records, and penalties for those that failed to comply fully with the law. The potential for harassment of various groups would be immense. The paper work alone might be enough to discourage some from engaging in these activities. This would be regulation run amok. Congress has enough trouble trying to trim back the rules already in effect, without jumping into a field that raises so many questions and threatens such infringements on political liberties.