As one longtime labor strategist put it of Obama: “He ain’t Carter, and there ain’t no Kennedy.”

“You can’t beat something with nothing,” continued this labor veteran, who is still working in the movement and didn’t want to be named. “And in the case of Obama, you better have a whole lot of something.”…

Robert Borosage, who heads the progressive Campaign for America’s Future, said he couldn’t imagine a primary challenge against Obama that would beat him.

“But you could imagine a challenge that would be destructive,” he said.