The president of Common Cause yesterday said the growing dependence of members of Congress on campaign contributions from political action committees has placed "representative government under seige."

"It's time to declare war on PACs," Fred Wertheimer, head of the self-designated citizens' lobby, said in a speech to the National Press Club.

"We are not obtaining the best judgment of our elected officials because they are not free to give it to us," he said. "PACs, through campaign contributions, are creating a higher obligation for our representatives, an obligation to serve PAC interests first and foremost."

In the 1982 campaign, PACs contributed $80 million to congressional candidates, up from $12.5 million eight years earlier. The average member of the 98th Congress received more than a third of his contributions from PACs, Wertheimer said.

The Common Cause antidote to the growth of PACs is partial public financing of congressional campaigns, a proposal that has been rejected every time it has been considered by Congress over the past dozen years.

Wertheimer acknowledged that it will be an "uphill fight" to pass such a bill in the 98th Congress, but he said the growing media attention and the public perception that Congress has placed itself "on the auction block" have given the matter a new urgency. "Issues have cycles in this country, and people's attention and interest are focused more than ever."

One roadblock to legislation is a lack of consensus--even among those who agree that the current campaign finance system needs fixing--on how to fix it.

The Common Cause proposal, embodied in a bill introduced late last year by Rep. David R. Obey (D-Wis.), would:

* Place a lid of $90,000 on what a House member could accept from PACs in a two-year election period. The current limit is a $5,000 ceiling (or $10,000 if a primary is included) on what members of Congress can receive from individual PACs.

* Allow a dollar-for-dollar match of federal funds to candidates who raise money in amounts of $100 or less from individual donors, providing they agree to a $20,000 limit on personal and family contributions and a $180,000 overall spending limit.

* Provide that if a candidate chose not to accept the limits, his opponent would receive a two-for-one dollar match and would not be bound by the overall spending limit.

* Provide compensation, in the form of free television response time or extra public funds, to candidates who are targets of "independent expenditure" PACs.

The opposition to such public funding is both economic and philosophic. Taxpayers should not be forced to finance the campaigns of politicians with whom they disagree, the argument goes.

While some Republicans dissent from this view, it will be left to the Democrats to carry the fight on public financing, many Hill observers agree.

But there are pragmatic disincentives for the party to take up that banner.

Democrats raised more money from PACs last year than did Republicans, which also was true in the five previous congressional elections. Thus, there is an element of "biting the hands that feeds" in any Democratic move to limit PAC contributions.

"If the Democrats tried to push a bill through the House without any guarantee they'd get it through the Senate, it'd be a real kamikaze mission," one Democratic staff member said.