According to Mishel's own report, the productivity of U.S. workers has risen by 80 percent over the past three decades. But hourly wages have only risen 11 percent.

Conservative economists disagree. Andrew Biggs is a resident scholar at the American Enterprise Institute.

“We have had significant differences in the way employee compensation is paid out. More goes to health care today than in the past. Less goes to wages and benefits. That is not a function of exploitation. That is a function of rising health care costs and those have to be borne out somewhere,” Biggs said.

Biggs argues that bringing down health care costs and increasing productivity will lead to higher wages.

Mishel does not believe that's true.

“... because we see wages have gone down for segments of the population that don’t even get health insurance,” Mishel said.

Meanwhile, union leader Tom Lee says he believes wages will continue to decline unless workers organize and press for policies that focus on economic security for all.