MoveOn.org would not get behind any deal that reduced Medicare, Medicaid, or Social Security benefits, said Ilya Sheyman, campaign director for the liberal group. The AFL-CIO, the nation’s largest labor federation, is equally adamant that benefits should not be cut.

“Our principles are non-negotiable and if the cost for getting the speaker of the House on board is to do something like cut taxes yet again for the rich or cut benefits to the social safety net, we are opposed,” said AFL-CIO spokesman Jeff Hauser, who added that it was better to go over the “fiscal slope” than to bend to Republican demands.

Representatives for the AARP, one of the most powerful lobbying groups in Washington, said that although they were open to having a conversation about ways to slow the growth of health care costs in a different context, they were appalled at the prospect that changes to vital entitlement programs could be ironed out in an end-of-the-year deal on budget and taxes.