The Democratic plan would extend benefits for the long-term unemployed until mid-November -- an increase from an original three-month proposal -- and would pay for it by extending for a year a part of the budget sequester's mandatory savings that would cut funds for Medicare providers. But it would delay those additional cuts until 2024.
Other savings would come from a crackdown on people who double-dip from the government by collecting both long-term unemployment benefits and Social Security disability benefits.
The original measure to restore jobless-benefits for three months would have cost $6.4 billion.
About 1.4 million Americans' benefits expired Dec. 28. The figure was initially reported as 1.3 million, but Reid said Thursday the number grew 100,000 so it was now 1.4 million.
Senate Republicans chafed at the proposed extension's jump to nearly a year from three months, as well as the Democrats' proposal to pay the cost by extending cuts out a decade.
They also rebelled against a move by Senate Majority Leader Harry Reid, D-Nev., that prevents them from proposing amendments to the measure.
Reid said the Democrats' proposal was "entirely paid for" and contained "structural changes" Republicans demanded.
"We've done everything the Republicans wanted," Reid said in remarks quoted by the Washington Post. "Now is the time to fish or cut bait."
He set up a showdown vote on the measure, most likely Monday night. His party needs at least five GOP senators to cross the aisle to support the plan.
Sen. Lisa Murkowski of Alaska, one of six Republicans who voted Tuesday to break a filibuster of the bill's original version, expressed shock at how the legislation was modified.
"When this was first presented it was a three-month emergency extension. Now all of a sudden we've morphed into a one-year. To me that doesn't sound like much of an emergency, certainly not temporary," she said in remarks quoted by Politico.
Sen. Dan Coats, R-Ind., said Reid's move to prevent amendments was emblematic of a Senate in which lawmakers are rarely allowed to vote on Republican legislation.
"That is not how the Senate works or is supposed to work," Coats said in remarks quoted by USA Today.
Sen. Rob Portman, R-Ohio, who had proposed ways of saving an additional $4 billion, said Reid didn't involve him in the negotiations.
Portman said he intended to work through the weekend to craft a different deal with Democrats.
"We haven't had the chance to sit down and talk about this," the Post quoted Portman as saying.
House Republican leaders jumped on Reid's move to postpone implementation of the sequestration offsets for 10 years, calling it a gimmick.
"That sounds like something the Senate would try to do. But I'm not going to opine," the Post quoted House Majority Leader Eric Cantor, R-Va., as saying.
House Speaker John Boehner, R-Ohio, said an extension of expired benefits would have to be paid for with conventional offsets.
He added he also intended to tie the measure to GOP priorities such as building the Keystone XL oil pipeline, expanding exemptions from the Affordable Care Act and opening energy exploration on federal land.