WASHINGTON — The House late Friday approved a Democratic-sponsored move to reform campaign finance laws by providing voluntary spending limits for congressional candidates and restricting contributions by political action committees.

The measure was adopted by a vote of 255 to 155. The vote was sharply divided along party lines.

Although not as far-reaching as a Senate reform bill approved earlier this week, the House measure still would be the most comprehensive overhaul of campaign finance laws since the Watergate era. Its passage was driven by public concern over mounting campaign costs financed largely by special interest groups.

The House and Senate bills now must be reconciled by a joint conference committee, which will meet in September after a monthlong congressional recess. Prospects are doubtful that the measures will wind up as law because White House officials have said that President Bush opposes any voluntary spending limits on congressional candidates.

Republican opponents of the House legislation protested that the reforms did not go far enough. They charged that keeping the PAC system intact, albeit with new limits, would protect many Democratic incumbents.

Other opponents in both parties, including House Ways and Means Committee Chairman Dan Rostenkowski (D-Ill.), complained that the reform proposal was being "rammed down the throats" of House members by the Democratic leadership on the eve of the August recess without the benefit of committee hearings.

The measure, which was brought directly to the House floor by a Democratic leadership task force, would limit each House candidate to $275,000 in PAC contributions per election.

In addition, it would set voluntary overall spending limits of $550,000 per House candidate and, as incentives, would offer lower congressional broadcasting and mailing costs for those who agree to the limits.

The legislation would allow in-state donors who contribute up to $50 to claim a 100% tax credit when giving to a candidate who has adopted spending limits.

The Democratic package fell short of campaign reforms that have been urged by outside "citizen lobbies" such as Common Cause and Public Citizen. But proponents called it "a first step" that would retard the escalating costs of congressional campaigns, help curb the growing influence of special interest lobbies and place more reliance on a member's constituents for political donations.