SACRAMENTO — Charging that escalating campaign costs have made politicians increasingly beholden to well-heeled special interests, backers of one of two term-limit initiatives on the November ballot are calling for a dramatic change in the way elections are financed.

Propositions 131 and 140 seek to overhaul state politics by forcing more turnover of elected representatives. But the public financing of campaigns, called for in Proposition 131, could bring a more immediate change in the political behavior of candidates for state office and the financial contributors on whom they depend.

In place of overwhelming reliance on special-interest money, Proposition 131 would set up a taxpayer-supported fund to pay up to half the costs of a candidate's campaign. The new rules would apply in every race for elected state office, including governor, attorney general and all members of the Legislature.

Supporters of Proposition 131 contend that public funding would work hand in hand with the measure's other provisions--term limits, a ban on non-election-year fund raising, and new restrictions on campaign spending and contributions. Backers say this combination of reforms seeks to loosen the grip that special interests--corporations, causes and institutions--have had on legislators.

"It would be the most comprehensive package of campaign reforms ever adopted in this country," said Robert M. Stern, the former general counsel for the Fair Political Practices Commission and a backer of Proposition 131.

Said Atty. Gen. John K. Van de Kamp, who drew up the initiative as part of his unsuccessful campaign for governor: "It's really going to open up the possibility for new faces (in elected office)."

But opponents of Proposition 131 argue that the campaign-funding provisions would increase the influence of special-interest money. They say that when limits on political committees are reached, individual corporate executives could respond by making sizable personal contributions--up to $40,000 spread over 40 campaigns. Less affluent people would not be able to give as generously, according to this argument.

Opponents also argue the initiative would give tax money to the campaigns of extremist candidates, and that by limiting campaign spending it would restrict free speech.