"In January, they [Republicans] will be in the majority and this [majority] would dramatically reduce their incentive to extend unemployment benefits, to support the conversion of Make Work Pay tax credit that President Obama enacted into this payroll tax [credit]," Clinton said.
"The results are what they are," he added later. "The numbers will only get worse in January, in terms of negotiating."
Clinton said he wasn't asked by the administration to speak to any particular lawmakers, and added that he has "no idea" if his appearance at the podium today will help sway votes.
The former president also urged senators to ratify the Strategic Arms Reduction Treaty (START) that has been stalled in partisanship.
"The START agreement is very important to the future of our national security and it is not a radical agreement," he said. "This is something that is profoundly important. This ought to be way beyond party."
Republicans say they want to deal with tax and spending issues first before voting on the START treaty.
Clinton also urged his fellow Democrats to fight against the repeal of the health care bill -- a key campaign issue for many Republicans -- and the repeal of the financial reform legislation.