Talk between Republican and Democratic lawmakers over the so-called fiscal cliff broke down at least temporarily Sunday in a dispute over whether Congress should start work on reforming programs like Medicare and Social Security.

With a Monday deadline looming, Senate Minority Leader Mitch McConnell, R-Ky., on Sunday made a personal plea to Vice President Joe Biden to intervene in the talks to help get them restarted.

Democrats are balking at a Republican proposal to include in any final deal a provision that would help reduce Social Security payments by changing the way the government accounts for inflation when calculating cost-of-living adjustments for beneficiaries, Senate aides and lawmakers told The Washington Examiner Sunday.

Republicans said the change not only would save money but begin the process of reforming two of the most costly federal programs, something Democrats wanted to put off until the new Congress convenes in January.

Democrats dismissed the GOP proposal, saying it would reduce payments to Social Security beneficiaries. One senior Democratic aide called the Republican demand a "major setback" for talks with just hours remaining to make a deal.

President Obama, appearing on NBC's "Meet the Press" Sunday, said he would accept a change in Social Security inflation calculation "in pursuit of strengthening Social Security for the long term."

Senate Majority Leader Harry Reid, D-Nev., later appeared on the Senate floor to announce that even though the GOP had offered a proposal, he had nothing to send as a counteroffer.

"We will continue to try to come up with something but at this time we don't have a counteroffer to make," Reid said.