President Obama's bid on Wednesday to offer a budget concession to Republicans by trimming the planned spending growth of Social Security is winning little support among progressives, with one former aide calling it a "doozy" of a mistake.

Activist and former aide Van Jones, who runs the influential anti-Tea Party group Rebuild the Dream, said, "I worked for this president. I voted for this president. But even the most beloved presidents make mistakes and missteps. This one would be a doozy."

Former Clinton Labor Secretary Robert Reich hit Obama too, claiming that the president's plan to recalculate down Social Security increases "would hurt seniors -- it's an idea not befitting a Democratic president."

Jim Dean, head of Democracy for America, is threatening to fund challenges to Democrats who back the president's move.

They're not alone in challenging Obama. Other opponents include the AFL-CIO, and the National Organization for Women.