With portable cots at the ready, the Senate lumbered crankily early today through a marathon session aimed at forcing passage of a new farm bill before Thanksgiving recess.

Majority Leader Robert J. Dole (R-Kan.), warning that failure to finish would kill the bill's chances this year, said he would keep the Senate in session until its work was done.

But Dole's pressure tactics appeared to backfire. Democrats angered by his refusal to consider more generous income supports for farmers threatened to stall the measure unless Dole relented.

Before Dole's express hit the roadblock, the Senate quickly rejected on a 56-to-36 vote a proposal by Tom Harkin (D-Iowa) to allow farmers to vote on mandatory production controls -- which the Reagan administration had warned would bring instant veto if included in the bill.

Tempers flared from time to time in clangorous debate over the tenuous farm economy and the Republican-led drive to force costs within budget limitations.

The commodity portion of the bill, concocted by Dole and other GOP leaders in back-room negotiations this week, generally would lower price supports while holding income support subsidies for farmers close to current levels.

In his desire to push a bill through the Senate and into conference with the House-passed version, Dole included a contradictory one-year and four-year freeze on income supports and said conferees would have to choose. The House backed a five-year freeze; the administration supports the one-year freeze.

But Democrats, led by Harkin and Sen. John Melcher (D-Mont.),complained that the GOP-dominated Senate conferees would stick with the one-year freeze, undermining their efforts to broaden the support package.

"We're not responsible for this mess," Harkin said. "We have a responsibility to try to do the best we can for our constitutents. We're gonna fight for what we believe in."

Dole, however, said, "We've had 85 hours of debate on this. I can't capitulate."

And there the deadlock stood at 2 a.m. today.

Minority sentiment to the administration view was further reflected by Sen. Dale Bumpers (D-Ark.), who was narrowly defeated in an effort to slow the bill's proposed reduction in soybean price supports.

"Let's not break them all at one time," Bumpers said of soybean farmers hit by rapidly falling prices and declining export sales.

In its first bow to budget-cutting demands, the Senate agreed yesterday to an amendment by Dan Quayle (R-Ind.) to phase out the support program for honey over the next three years. A motion to table his amendment lost, 60 to 36.

The Agriculture Committee bill would have continued the honey program, at lower support rates, but Quayle called it "one of the sweetest rip-offs to come along in a long time." He said that federal purchases of surplus honey from a handful of large producers had "stung" taxpayers to the tune of $100 million a year.

But the Senate refused to go against the committee yesterday on two other controversial key amendments -- one that would have scaled down the sugar support program and Harkin's referendum for wheat and feed grain farmers.

Both issues had been among the most heavily lobbied during the farm bill debate that began last winter. Sugar interests mounted an intensive campaign in recent weeks to save their program; agribusinesses turned up the heat against the mandatory control proposal.

The efforts paid off.

Sens. Bill Bradley (D-N.J.) and Slade Gorton (R-Wash.), attempting to cut the sugar program, saw their motion tabled on a 60-to-32 vote, even though they had the support of the administration. The bill will keep the floor under domestic sugar prices at 18 cents per pound over the four-year life of the bill.

The intensity of the fight over sugar was reflected by J. James Exon (D-Neb.), who accused the sugar lobby and sugar-state senators of treachery in breaking up the "commodity family" with their resistance to cuts in the program.

The referendum idea, rapidly gaining farmer support, was rejected handily, with the help of administration threats of a presidential veto.

Harkin, the chief sponsor, argued that production controls were the only way to stop the decline in farm prices and bring supply back in line with demand. He said the proposal would cut government costs, put the bill under budget limits and increase net farm income by $8.5 billion, while adding only 9 cents a day to the average American's food bill.

Dole called the amendment "so bad we don't need much time." He said mandatory controls would price U.S. grain out of export markets and drive up costs for domestic livestock producers.