Senate Democrats yesterday agreed to a Republican proposal to outlaw political action committees (PACs) and sharply modified their proposal for public financing of Senate campaigns, claiming the moves could lead to a break in the partisan impasse over campaign finance reform.

The Democratic concessions, which were received with a noncommittal response from the office of Minority Leader Robert J. Dole (R-Kan.), came as the Senate prepared to begin debate Monday on a major overhaul of Congress's much-criticized system of financing campaigns.

"We'll see them on the {Senate} floor and hope we can work something out," said Dole spokesman Walt Riker.

Sen. Mitch McConnell (R-Ky.), floor manager for the GOP bill, welcomed the concession on PACs but said the new federal funding plan was "blatantly unconstitituional."

At least on the issue of banning PAC contributions, Democrats appeared to be bowing to the reality of a likely GOP victory and evading the political damage that could occur from failing to take an unambiguous position against this form of special-interest influence in campaigns.

The Democratic proposal also came only a day after Democrats rejected a GOP proposal, which Republicans had characterized as a "deal-maker," and gave the Democrats the last word -- for the time being -- in the contest between the two parties for credit in spearheading reform.

But Sen. David L. Boren (D-Okla.), chief sponsor of the Democratic bill, said the move was aimed "more to show we're really serious" about getting a compromise that can be passed by both houses and signed by President Bush.

Even with agreement on PACs and a narrowing of differences over public financing, however, the parties remain deadlocked over the key obstacle to agreement: state-by-state spending limits for campaigns, which the Democrats favor and the Republicans oppose.

"We've extended a hand to the other side of the aisle. They have not been easy steps to take," said Boren, expressing hope that Republicans would now reciprocate by agreeing to spending limits. If they do, he said, "we can have a bill."

Democrats previously agreed to prohibit PAC contributions to Senate candidates but would have allowed continued PAC giving to parties and their committees. The GOP bill calls for a ban on all PAC contributions in federal elections, with a standby provision for a limit of $1,000 on PAC gifts to a candidate if the Supreme Court rules that a total ban violates free-speech provisions of the Constitution. The Democratic bill incorporates the standby provision of the Republican bill and also includes aggregate limits for PACs, Boren said.

As an incentive to encourage compliance with voluntary spending limits, Democrats had also proposed partial federal funding of campaigns, along with reduced postal rates and broadcast subsidies, to candidates who accept the spending caps. The Republican bill contains no direct taxpayer-financed funding of campaigns. The new Democratic proposal would keep the postal and broadcast provisions but allow direct federal funding only for a candidate who abides by spending limits and faces an opponent who refuses to do so, Boren said. McConnell said use of federal funding to punish those who do not accept spending limits would be unconstitutional.