Senate Majority Leader Harry Reid delayed a key vote Monday on restoring long-term jobless benefits to nearly 1.4 million unemployed Americans, as he wrangles behind closed doors with Republicans over a potential deal to win their crucial support.

Reid needs help from six Republicans to get the 60-vote majority needed to advance the $18 billion, revised legislation to a final vote.

“It’s been difficult for me and I’m quite certain for the Republican leader to talk to all the necessary people … on how we should proceed on this legislation,” Reid said.

Six Republicans gave their support last week to the original plan that cost $6.4 billion and extended the program for three months. But they -- along with three other Republican senators -- were asking for a list of concessions in exchange for support of the revised, 11-month plan, including a vote on amendments for job training and near-term spending cuts to offset the benefits expense.

The benefits expired Dec. 28 after not being renewed in the spending bill Congress passed before leaving for winter break.

A statement issued Monday night by the GOP senators negotiating the plan said, "we are all encouraged that we are making progress on a package that could pass with bipartisan support.  The proposal includes (1) a three-month extension of the temporary federal long-term unemployment insurance program; (2) a repeal of the recent cuts in the military retiree cost-of-living adjustment included in December's budget agreement; and (3) offsets to pay for the unemployment extension and restoring military retiree benefits within the budget window."

The legislation provides federal benefits for the unemployed who have exhausted their state-provided support, generally 26 weeks.

The original legislation, which costs $6.4 billion, restored the program for three months.

Reid met during the day with Republican Sens. Dean Heller, Nevada, and Susan Collins, Maine, two of the six Republicans who helped push the legislation over an initial hurdle last week.

He said afterward they have made a proposal for a three-month plan.

“However, I can’t automatically agree to it because … as everyone knows the president’s not in favor of a three-month proposal, and I’m not either. … But that doesn’t mean we can’t work something out.”

The other four Republican senators who voted in favor last week were Dan Coats, Indiana; Lisa Murkowski, Alaska; Rob Portman, Ohio; and Kelly Ayotte, New Hampshire. They were joined in the new "gang of nine" by John Hoeven,North Dakota; Orrin Hatch, Utah; and Mark Kirk, Illinois.

Under the expired program, the long-term jobless were entitled to a maximum of 47 additional weeks of benefits, depending on the unemployment level in their states.

The total would fall to a maximum of 31 weeks, according to the revised bill Reid advanced late last week.

After initially rebuffing Republican calls to pay for the program, Democrats proposed offsetting the cost in part by extending previously approved cuts to Medicare providers by one year, through 2024.

Senate Minority Leader Mitch McConnell of Kentucky blames Democrats for the hold-up, saying Reid appears to want to extend the program “without really paying for it, without doing much of anything to help create private-sector job creation and without creating opportunities for targeted training" for the unemployed.

Reid’s office said Friday that Senate leadership is “absolutely willing” to consider a reasonable number of relevant GOP amendments.

But Republicans remain skeptical about whether Reid will allow Republican input.

What the majority leader considers "reasonable" is yet to be seen, a Capitol Hill Republican told Fox New.

Since last summer, Reid has allowed votes on only four Republican amendments, compared to votes on 71 Democrat amendments.

Fox News’ Mike Emanuel and the Associated Press contributed to this report.