Vermont Senator Bernie Sanders. (AP Photo/Rich Pedroncelli)

President Obama’s plan to include Social Security cuts in his budget plan is well summed up by Vermont Senator Bernie Sanders as a “bitter disappointment.”

Obama closed his 2012 campaign with a populist flourish that seemed to suggest he was finally coming to believe his own rhetoric about the need for growth, as opposed to austerity. The strength of his message earned the president a mandate: a popular vote margin of almost 5 million, a landslide win in the Electoral College and significant gains in Senate and House races.

But now, he proposes to squander that mandate in pursuit of a “grand bargain” with House Republicans—a bargain that would replace the current approach to calculating cost-of-living increases for Social Security recipients with a “Chained-CPI” scheme. The change will harm not just seniors, children and people with disabilities, but a fragile economic recovery.

Additionally, the president is reported to be prepared to propose some means testing for Medicare.

This is not Paul Ryan privatization. But it is a classic austerity cut.

It is wrong economically, and politically.

“Social Security is not driving the deficit; therefore it should not be part of reforms aimed at cutting the deficit. The chained CPI, deceptively portrayed as a reasonable cost of living adjustment, is a cut to Social Security that would hurt seniors,” says former Secretary of Labor Robert Reich. “There are several sensible reforms to Social Security that should be considered to help make it sustainable, including lifting the ceiling on income subject to Social Security from $113,700 to $200,000 or more, as well as instituting a 1 percent raise in the payroll tax rate, a rate that hasn't changed in over 20 years.”

Reich, a Democrat, warns that the president’s plan abandons a historic partisan commitment.

“(Ever) since Social Security's inception in 1935 and Medicare's 30 years later, Republicans have been trying to get rid of them. If average Americans have trusted the Democratic Party to do one thing over the years, it's been to guard these programs from the depredations of the GOP,” explains the former Clinton administration Cabinet member. “Why should Democrats now lead the charge against them?”

The president’s pursuit of a “grand bargain” was quickly rejected by House Speaker John Boehner.

Yet, despite the record of Republican obstruction, the White House has placed a major Social Security cut on the table.

“Social Security is too important to the economic security of the American people to be used as a bargaining chip. The president's own Secretary of the Treasury and former Director of the Office of Management and Budget has written about the budget,” says Nancy Altman, a founding co-director of Social Security Works. “The problem is not Social Security; the problem is the mismatch between outlays and revenues in the rest of the budget.' Applying the so-called chained CPI to Social Security cuts the benefits of every single Social Security beneficiary, now and in the future. The very groups who worked the hardest and voted in the highest percentages to re-elect the president—working families, women, people of color, young Americans—will be the ones hurt the most by the cuts the president is reportedly including in his budget.”

That’s a message that was echoed frequently Friday, as progressives pushed back against the president’s plan.

“What the president is proposing is going to hurt a lot of people,” said Sanders.

The senator from Vermont is not going to let that happen without a fight. He has launched a petition opposing the president’s approach. It reads:

At a time when the middle class is disappearing, poverty is increasing and the gap between the rich and everyone else is growing wider, we demand that the federal budget not be balanced on the backs of the most vulnerable people in our country.

A federal budget that reduces the deficit by cutting cost-of-living adjustments for Social Security and disabled veterans, raising the Medicare eligibility age and lowering tax rates for the most profitable corporations in this country is not a grand bargain. It is a bad bargain.

We oppose the chained-CPI, a new way to measure inflation and consumer prices designed to cut benefits for Social Security recipients, disabled veterans and their survivors.

We are strongly opposed to benefit cuts to Social Security, Medicare, Medicaid, education, and the needs of our veterans.

We demand a budget that puts millions of Americans back to work in decent paying jobs.

We demand a budget that makes sure that the wealthiest Americans and most profitable corporations pay their fair share.

Within hours of the White House confirmation of the president’s plan, the petition had already attracted more than 33,000 signatures.

At Indiana University, budget cuts are only one chip in the austerity game. Read StudentNation's primer on the campus-wide strike happening this week.