Progressive groups and lawmakers, including Sen. Bernie SandersBernie SandersSenate Dems: Don't leave for break without Supreme Court vote Sanders: Young voters will 'come on board' Clinton's campaign The Trail 2016: The fallout MORE (I-Vt.), are blasting the Obama administration for cuts to Social Security and other programs expected to be unveiled in the president's budget next week.
One progressive group, Democracy for America, is threatening primary challenges to those Democrats who support the cuts.
“The Senate just last month went on record in opposition to the president’s approach. In poll after poll, the American people are overwhelmingly against cutting Social Security. And organizations representing a broad spectrum of millions of Americans from the AFL-CIO to the American Legion to AARP to NOW have urged the president not to make this terrible mistake," Sanders said in a statement.
Sanders has previously suggested he may filibuster any budget proposal that includes cuts to entitlements.
Sanders' response is emblematic of a wider backlash among progressives against Obama's expected proposal on entitlement reform.
Senior administration officials confirmed Friday that the president's budget, to be released next Wednesday, would embrace "chained CPI" and would also reduce spending on Medicare through lower payments to healthcare providers and pharmaceutical companies.
Congressional Progressive Caucus co-chairs Reps. Raul Grijalva (D-Ariz.) and Keith Ellison (D-Minn.) echoed Sanders' opposition to chained CPI.
"Republicans have been trying to dismantle Social Security ever since President Roosevelt proposed it during the Great Depression. We should not try to bargain for their good will with policies that hurt our seniors, especially since they’ve been unwilling to reduce tax loopholes for millionaires and wealthy corporations by so much as a dime," they said in a joint statement.
Rep. Jerrold Nadler (D-N.Y.) also issued a statement.
“I am quite concerned by reports that the forthcoming White House budget proposal might include chained CPI and other accommodations to Republicans determined to dismantle our social safety net and the progress our nation has made since the New Deal," Nadler said. "I must reiterate that I will never support any reductions in Social Security, Medicare or Medicaid benefits – and chained CPI is a direct reduction in Social Security benefits. Along with my fellow progressives, I will vehemently oppose any such cuts."
Progressives in Congress are supported in their opposition to the proposal by a number of progressive groups that have already expressed staunch opposition to any cuts to Social Security or Medicare, with some suggesting they could make this an issue in the 2014 elections.
DFA spokesman Neil Sroka said outright that the group will launch primary challenges against Democrats who support the president's plan.
"Any Democrat that votes to cut Social Security, Medicare and Medicaid benefits is at risk at facing a primary challenge. These are bedrock principles for the millions of progressives who are the backbone of the Democratic Party and have been organizing to protect this for years," he told The Hill.
"Siding with the president in support of these cuts is tantamount to declaring war on the Democratic base who helped elect every one of these Democrats, and it will be responded to as such," he added.
Stephanie Taylor, co-founder of the Progressive Change Campaign Committee, warned that "progressives will do everything possible" to prevent the cuts.
"You can't call yourself a Democrat and support Social Security benefit cuts. The president is proposing to steal thousands of dollars from grandparents and veterans by cutting cost of living adjustments, and any congressional Democrat who votes for such a plan should be ready for a primary challenge. Social Security is the core of the progressive and Democratic legacy. The President has no mandate to cut these benefits, and progressives will do everything possible to stop him," she said in a statement.
Becky Bond, political director for CREDO, a progressive group that has engaged heavily in the gun control debate, called for Democrats to oppose Obama's proposal.
"Our negotiator-in-chief is now serving up cuts to Social Security benefits in a mystifying attempt to appease Republican hostage-takers in Congress," she said.
"The American people are overwhelmingly opposed to cutting Social Security benefits, and if Democrats don't want to go down in history as the party that destroyed one of the greatest social programs of all time, they need to stand up and unambiguously reject the president's proposed cuts."
The president's proposal is an attempt to offer Republicans concessions in exchange for some movement on taxes. The White House said the president will only agree to entitlement reform in exchange for tax increases on the wealthiest Americans and corporations.
But progressive groups say they won't stand for any cuts whatsoever on Social Security and other entitlements, and Democracy for America in particular pledged to activate its grassroots network to fight the battle out at the polls.
"I would be more worried about the grassroots backlash from the Left, Right and center if you support these cuts, than the backlash if you came out and took a bold progressive stance," Sroka said.
Updated at 2:16 p.m. and 3:15 p.m.