Gridlock asserted itself after majority Democrats offered to pay for a 10-month extension of a scaled-back program of benefits — then refused to permit Republicans even to seek any changes.
Instead, Majority Leader Harry Reid, D-Nev., accused Republicans of "continually denigrating our economy, our president and frankly, I believe, our country."
But Sen. Dan Coats of Indiana, one of a half-dozen Republicans who helped advance the bill over an initial hurdle earlier in the week, said he hadn't been consulted on any compromise.
Echoing complaints by other members of his party, he said that under Reid's leadership he has been relegated to the sidelines. Indiana voters "didn't send me here to be told just to sit down and forget it," he said.
At issue was a struggle over the possible resurrection of a program that expired on Dec. 28, immediately cutting off benefits of roughly $256 weekly for more than 1.3 million hurt by the recession.
The measure is the first to come before the Senate in the election year, and since Monday has become ground zero of a competition between the political parties to appeal to hard-hit victims of the longest recession in more than a half-century.
While unemployment has receded in recent months, long-term jobless is high by historical standards.
Despite the squabbling, lawmakers in both parties said the effort to find a compromise would continue.
"We're still trying to work through this," said Sen. Jack Reed, D-R.I., whose state has 9 per cent unemployment.
At midday Thursday, Reid had expressed optimism about the chances for compromise, and Democratic officials said talks with Republicans were focused on a scaled-back program that is fully paid for and would provide up to 31 weeks of benefits for the long-term unemployed.
The officials said the proposal would run through the late fall, and the price tag — approximately $18 billion — would be offset through cuts elsewhere in the budget so deficits would not rise.
Reid told reporters he was "cautiously optimistic" about a compromise emerging later in the day, and said he had held meetings with fellow Nevadan Dean Heller, a Republican, but provided no details.
But midafternoon, when Reid formally outlined the proposal, there was no evident Republican support for it, and each side accused the other of an unwillingness to compromise.
Chandler Smith, a spokeswoman for Heller, said the senator met with Reid and Reed during the day and has been talking with Republicans as well, although he spent part of the day at a hospital for repair of a cast.
Heller "remains optimistic, and appreciates that Sen. Reid has been negotiating in good faith to reach a deal," Smith said.
Democrats initially sought a three-month renewal of the expired program and opposed paying for it, meaning the $6.4 billion cost would be added to the deficit.
Republicans countered that any legislation must be offset by cuts elsewhere in the budget. Among their proposals was one to delay the requirement for individuals to purchase health care under "Obamacare," and another to prevent immigrants living in the United States from claiming a certain type of tax credit for their children.
They said either would pass easily, a claim Democrats did not dispute. But rather than exposing his rank and file to a politically hazardous vote, Reid made sure they were not formally offered.
The expired law provided a maximum of 47 weeks of payments after an unemployed worker has exhausted state-funded benefits, usually 26 weeks.
The new measure would reduce the 47 weeks to a maximum of 31 weeks, officials said, based on a sliding scale that dates to the expired program.
The Democratic officials said the first tier of additional benefits would be six weeks, and be generally available to all who have used up their state eligibility.
They said an additional six weeks would be available in states where unemployment is 6 per cent or higher; an additional nine weeks in states with joblessness of 7 per cent or higher; and 10 more weeks in states where unemployment is 9 per cent or more.
The cost would be offset in part by extending a previously-approved reduction in Medicare payments to providers, the officials said, and in part by limiting or eliminating the ability of individuals on Social Security disability from also receiving unemployment benefits.
The officials who described the details of the possible legislation did so on condition of anonymity, saying they were not authorized to speak on the record.