"The task looks Herculean because, as most economists would argue, the U.S. is riding on a slow-moving turtle and there is little politicians can do about it.  This view is founded on the evidence of a secular decline in aggregate total-factor-productivity (TFP) growth—a widely used indicator of technological progress, fondly known as and measured by the ‘Solow residual’. 

"Dwindling TFP growth, which is in this view taken to reflect a general malaise in exogenous ‘technology-push’ innovation, reduces the rate of growth of potential U.S. output—this is the slow-moving turtle.  

"Potential growth is exogenous if one assumes, as is commonly done, that the alarming crisis of U.S. productivity growth crisis is exclusively due to supply-side factors such as excessive (labor market) regulation, undue business taxes, an insufficiently skilled labor force, and too little competition (also from abroad)."