Sponsors of the Senate campaign finance bill said yesterday they will narrow its scope and focus on banning unregulated "soft money" contributions to political parties, hoping to avoid pitfalls that have killed previous reform efforts in the Senate.

Provisions such as restrictions on campaign season issue ads would be dropped but could be added back by amendment, along with other proposals that could help produce the 60 votes needed to break a promised Republican filibuster, according to sponsors John McCain (R-Ariz.) and Russell D. Feingold (D-Wis.).

But their plans could be complicated by Democrats' plans to force a vote on the original bill, which was supported by a majority of the Senate last year, and Sen. Mitch McConnell (R-Ky.), chief foe of the bill, said the narrower proposal was unlikely to pick up GOP support.

McCain and Feingold agreed on the new strategy after lengthy consultations with colleagues and plan to introduce the scaled-back bill today. Debate and votes are scheduled for mid-October.

The two senators disclosed their plans in the wake of a 252 to 177 vote in the House late Tuesday to approve legislation that was almost identical to the original McCain-Feingold measure. While they said the vote bolstered their hopes for success in the Senate, they were still as many as eight votes short of the 60 needed to force passage.

"Obviously the whole strategy is to let people be involved in the process, to propose amendments to improve it and see if we can't get 60 votes," McCain said in an interview. "The objective is to get a bill passed and sent to conference [with the House]. I would much prefer it to be more, but the objective is to get 60 votes."

In the past, opponents have been able to "nitpick at one or another provision in order to kill the whole thing," Feingold added. "Now we're asking if you're for or against the soft-money provision and inviting other ideas."

Shelving the provision to restrict corporation- and union-financed issue ads that target specific candidates as elections approach also "makes it much more difficult to use the First Amendment argument against the bill," Feingold said. Critics have argued that such restrictions curb free speech rights guaranteed by the amendment.

The centerpiece of the revised bill will be the proposal to bar corporations, unions and wealthy individuals from using the device of soft money to channel unlimited, unregulated contributions to political parties for use in federal campaigns.

In an effort to address GOP concerns about other labor expenditures on elections, the bill would write into law a Supreme Court decision requiring labor unions to notify nonmembers that they can have the fees they pay in lieu of union dues reduced to exclude the cost of a union's political activities.

This provision is far less controversial than a proposal offered last year by Majority Leader Trent Lott (R-Miss.) that would have required union members to give explicit approval before their dues could be used for political purposes. The Lott proposal is anathema to Democrats and was rejected by the Senate and House.

It was not clear yesterday whether the new McCain-Feingold strategy would pick up enough votes to succeed. "I know we can get additional votes . . . but I don't know if we get to 60," said McCain.

The problems they face were illustrated by two senators regarded as sympathetic to their cause: Sens. George V. Voinovich (R-Ohio) and Chuck Hagel (R-Neb.).

Voinovich said his primary interest is additional curbs on use of union dues for politics, arguing that Republicans in states such as Ohio will be unable to compete with union spending if they give up soft money, where they have an edge over Democrats.

An aide to Hagel said Hagel is most interested in "full, immediate disclosure" of all money spent to influence elections and would limit rather than ban soft money because of concern that a ban may be unconstitutional.

Senate Democrats were unhappy with the authors' decision, arguing that the legislation keeps getting trimmed back in futile efforts to make it more palatable to Republicans. "At some point there's no meat on the bones," said Sen. Byron L. Dorgan (D-N.D.). Sources said Democrats would not, however, oppose a scaled-back bill.