Chances for final action this week on a new farm bill plunged yesterday as House and Senate conferees became mired in deep disagreement over the crucial issue of income supports for farmers.

The conferees spent most of the day dodging final decisions on less controversial sections of the bill, then went into gridlock last night over the amount of income "safety net" that the measure should provide.

Senate Majority Leader Robert J. Dole (R-Kan.), attempting to force the issue with a new compromise proposal, renewed warnings that the conferees' inaction threatened chances for producing a bill this year.

Dole indicated that he might keep the Senate in session next week by delaying other key legislation while farm bill conferees continue their work. "What we from farm states are fearful of is that we won't find a quorum around here next week to vote on a farm bill," he said.

But Dole's compromise, more generous than the administration has said it would accept, was rejected by House Democrats and Republicans, leaving the two sides at wide odds and dashing the possibility of a quick settlement.

After several votes on proposals by each side, a conferees' subcommittee late last night produced another approach, in effect a three-year freeze, that appeared to win tentative support.

That proposal, termed "veto bait" by conference chairman Jesse Helms (R-N.C.), is to be taken up when the conference resumes today. Sen. John Melcher (D-Mont.), who earlier had warned that he would block anything less than a three-year freeze, indicated that he could support the new proposal.

But, he told Dole, "when we make a proposal that says a two-year freeze is what will save a veto, it is sort of like playing chicken. It is philosophy, or perception, not cost, that would cause a veto.

"On this, the administration cannot win, and it doesn't deserve to win. Whether we have a safety net there for farmers is for Congress to decide. I just don't understand that the administration has not learned over the last 11 months that that is the issue," he said.

The split between the White House and farm-state legislators over deficiency payments -- direct subsidies to those who farm wheat, corn, rice and cotton -- has persisted throughout the year-long debate on farm policy.

The administration wants a one-year freeze of the payments, with modest reductions in later years, to reduce budget costs and dissuade farmers from overproduction. The Senate adopted a two-year freeze and the House a five-year freeze.

Although the administration says a four-year freeze would cost $12 billion more than a one-year freeze, farm-belt lawmakers have insisted on maintaining higher income supports to compensate for lower market prices mandated by both bills.

Dole's new proposal calls for a two-year freeze on payments to wheat and corn farmers, with later cuts to be cushioned by giving farmers surplus commodities. No House conferee supported the offer.

A House counter by Rep. Thomas S. Foley (D-Wash.), a four-year freeze with part of the payments in commodities, was rejected by Republican-led Senate conferees, 5 to 4, on a party-line vote. Other proposed variations met similar fates.

Although agreement seemed nearer on the deficiency payments, another subcommittee continued working at odds last night on the equally thorny dairy-support issue. Participants indicated progress but apparently not enough to meet administration demands.

The impasse over income supports was only one of several issues that the conferees could not settle. Others included disagreements over controversial marketing orders, tighter quotas on imported sugar and how to deal with cargo-preference shipping law.