"I think it is clear that we can't go back to the type of policies that exacerbated the rise in inequality and threatened economic mobility in the first place if we want an economy that builds the middle class," Krueger told a packed room at the Center for American Progress.
The solidifying message comes amid persistent high unemployment and a renewed focus on inequality in 2011 partly due to the Occupy movements -- as well as an increasing air of inevitability that the Republican presidential nominee will be Mitt Romney. Democrats are working hard to paint him an out-of-touch one-percenter who would exacerbate the problem.
Central to the message is that inequalities in the system are "jeopardizing our tradition of equality of opportunity," as Krueger put it.
"If we had a high degree of income mobility we would be less concerned about the degree of inequality in any given year. But we do not," he argued. "Moreover, as inequality has increased, evidence suggests that year-to-year or generation-to-generation economic mobility has decreased."
Romney has taken to decrying this message as the "politics of envy" and "class warfare" -- an attack on success itself.
Krueger's speech Thursday makes clear that that's a fight the White House is happy to have.