A new study by Ralph Nader's Congress Watch charges that the U.S. Chamber of Commerce and the Business Roundtable exert massive and sometimes malign lobbying influence in the nation's capital. It said the Chamber acts as a public opinion battering ram in congressional districts and the Roundtable through inside manipulation at the highest levels of government.

The study said the Chamber or Roundtable had been instrumental in recent years in killing or weakening major consumer legislation. It cited proposals to strengthen the antitrust laws, impose criminal penalties for certain acts by corporate executives, revise the labor laws and give consumers a voice through a consumer protection agency. It said the Roundtable helped get Sen. Edward M. Kennedy (D-Mass.) to revise his corporate crime provisions in the criminal code.

The study, prepared by Mark Green and Andrew Buchsbaum, said the Chamber's power comes mainly from getting home district businessman to try to influence members of Congress with personal contacts and heavy mailings on issues taken up by the Chamber.

With its big budget of $30 million a year, nationwide staff of 1,200, membership of 94,000 business groups and firms and use of computers to reach key businessman quickly and to outline the effect of legislation on each congressional district, the Chamber Chamber acts as a powerful lobbying force from the grass roots, the Nader study concluded.

"By far its most influential activity is indirect lobbying -- sending information and advice to its members so they can in turn contact their congressman."

The Business Roundtable, on the other hand, according to the study, achieves its effect both with the executive branch and Congress through the prestige and even awe in which government officials held the 192 chief officers of the nation's biggest corporations. They make up the Roundtable, which is not a mass member organization.

It is simply impressive to a politician, according to the study, when they are buttonholed by the greatest captains of industry, with a particular point of view.

The study quotes former AT&T Chairman John deButts saying that President Carter at first told industry titans to make their views known through Cabinet members Juanita Kreps (Commerce Department) and Michael Blumenthal (Treasury). But "we finally told him, 'That's fine Mr. President. But we have to talk to you. If you want something from us, you don't talk to some executive vice president. You ask for the cheif executive officer. Well, we want the same thing.'..."

DeButts is quoted as adding, "We don't have any trouble getting to Carter now. Or Fritz Mondale. He's very easy to get to. I talk to Fritz Mondale fairly often."

Because it relies on the top men in each corporation to make the pitch personally, the Business Roundtable does not maintain a huge staff -- only about nine people with a $2.5 million annual budget. However, according to Green and Buchsbaum, individual businesses pick up a considerable amount of cost for some of the economic studies that end up in Business Roundtable position papers and testimony.

Wallace Bates, president of Business Roundtable, said in a phone interview that he had not seen the Nader report yet and could not comment.

However, Jeffrey Joseph, Chamber of Commerce director of governmental and regulatory affairs, called the study a "typical Nader study, a lot of facts, some true, some not ture, put together in a way to leave the impression he wants."

As for specializing in grass-roots lobbying, "we don't deny it, that's what we've always told people we do. We always have."