Senate Republican leaders agreed yesterday to schedule votes by mid-October on legislation to overhaul the nation's campaign finance laws, averting an immediate fight that could have tied the Senate in knots and delayed passage of critical spending bills.

Sens. John McCain (R-Ariz.) and Russell D. Feingold (D-Wis.), the bill's co-sponsors, had pushed for its consideration this week. But they said they were pleased by the agreement because it allows for votes on amendments under a fair and orderly process that enhances prospects for the legislation after two decades of struggle. With such a process, Feingold said he believes he and McCain are within reach of the 60 votes needed to break another in the long line of GOP-led filibusters that has blocked passage of the legislation over the years.

But McCain conceded they are at least six votes short. And Sen. Mitch McConnell (R-Ky.) said he sees no chance of 60 votes for the bill in its current form. McConnell noted that both sides will be able to offer amendments and said he regarded the process as mutually beneficial.

The McCain-Feingold bill, which got 52 votes in a showdown late last year, would ban unlimited, unregulated "soft money" donations to political parties from unions, corporations and wealthy individuals -- an increasingly deep source of money for political campaigns. It also would curb use of issue advertising late in a campaign when it targets individual candidates by name.

McCain said he and Feingold may modify their proposal to help pick up votes, such as leaving the issue ads proposal to the amendment process, but added that they expect the bill will closely track the legislation that they proposed last year.

McCain outlined several amendments that might be offered to broaden support for the bill, including an increase in the $1,000 limit on individual donations to candidates, tax incentives for small donors and a requirement that both unions and corporations get the permission of members and stockholders before using their funds for political purposes.

One potential problem is that some of the proposals that might attract Republicans could trigger objections from Democrats, who provide the bulk of support for the measure. In last fall's vote, all 45 Democrats voted to end the filibuster, along with McCain and six other Republicans.

The agreement, negotiated between McCain and Senate Majority Leader Trent Lott (R-Miss.), requires Lott to bring the campaign finance issue to the Senate floor by Oct. 12. McCain and Feingold would have to file their bill by Sept. 14.

There would be four days of debate and votes, during which amendments could be considered. McCain said the bill's opponents would be barred from blocking consideration of such amendments by parliamentary tactics, as they did last year.

The agreement anticipates another filibuster by Republican foes of the legislation and gives the bill's sponsors one chance at the end of the process to muster the 60 votes needed to break it. If that fails, the bill's sponsors would not raise the issue for the rest of this session of Congress but could do so next year.

House Republican leaders have scheduled votes on similar legislation by mid-September. Like Senate Republican leaders, they fended off pressure for earlier votes. But McCain and Feingold said they believed momentum for passage will increase with both houses considering the measure at roughly the same time.

CAPTION: Sen John McCain (R-Ariz.) said his bill is six votes short of filibuster-proof majority on campaign reform measure set for Senate vote this fall.