If nothing else, the departing 95th Congress amply demonstrated why there is so much popular demand for public financing of House and Science election campaigns.

as a glance at the performance of the 95th shows, the price of private campaign financing is the election of a legislative body that often is at the back and call of the special interests who now put up most of the money for congressional races.

Although the 95th was as responsible as the administration sometimes charged, the growth of government-by-pressure-groups is spawning something akin to chronic stalemate on the Hill, with Congress and the president frequently vetoing each other to a standstill.

After the notable sucess of public financing of the presidential campaign in 1976, it appeared that extension of that principle to congressional elections would have clear sailing but bills to that effect were filibustered to death in the Senate and derailed in the House by procedural maneuvers.

Meanwhile, the big money that special interests used to invest in presidential contests has been diverted to congressional elections. Literally hundreds of new political action committees (called PACs) have set up to push the interests of every imaginable group.

In 1976, these groups gave $22.6 million to congressional campaigns compared with only $12.5 million in 1974. This year they are expected to pour in $40 million or more, and the money is targeted for maximum influnce.

The last time around, the 14 major committee chairman who largely control the Senate got $900,000 in campaign contributions from the PACs, who also provided nearly two-thirds of the money that 15 key House committee chairmen spent to get re-elected.

The former chairman of the House Merchant Marine Committee, notoriously susceptible to private pressure, had a blunt answer when asked why he accepted huge contributions from the maritime shipping interests.

"Who in the hell," he said, did they expect me to get it from - the post office people, the bankers? You get it from the people you work with, who helped some way or another. It's only natural.

In new study on "How Money Talks in Congress," Common Cause cities numerous instances where the PACs have sucessfully used their influence to promote their own particular interests while killing or obstructing legislation they were against.

The Common Cause report shows in detail how some bills, including hospital cost controls and no-fault insurance, were knocked out, while effective road-blocks were placed in the way of electoral and tax reform, consumer protection, labor-lae reform and gun regulation, among others.

There is also the threat of corruption in the private financing of legislative races, as was demonstrated so well by Tongsun Park's efforts to buy influence for South Korea with almost $1 million in campaign contributions and payments to key congressmen. In addition, other members of the House and Senate are under indictment or investigation in connection with political payoffs of one kind or another.

Sen. Russell Long (D-La), chairman of the Senate Finance Committee, says the "distinction between a campaign contribution and a bribe is almost a hairline difference." And he adds: "Investments in this area can often be viewed as monetary bread passed upon the water to be returned a thousandfold."

Says Sen. Edward Kennedy (D-Mass): "Representative government on Capitol Hill is in the worst shape i have seen in my 16 years in the Senate. The heart of the problem is that the Senate and House are awash in a sea of special-interest lobbying and special-interest campaign contributions."

Three years ago, there were only 600 PACs in action, but today there are 1,709. Meanwhile, the number of lobbyists in Washington has soared from 8,000 to 15,000 in just five years, and more are on the way.

The Wall Street Journal, noting how the PACs are investing in Democrats as well as Republicans, quotes one congressman as saying, "Business already owns one party, and now it has a lease, with option to buy, on the other."

Neverthless, prospects remain bright for the adoption, possibly even next year, of public financing of congressional campaigns. Sentiment continues to grow for the reform in both the upper and lower chambers, and all the latest polls show overwhelming popular support, not only for public funding, but for the outlawing of all other contributions.