A host of economic landmines reportedly may prevent President Donald Trump from achieving the 3 percent economic growth he has promised. One economist bluntly predicts that the president would need a “productivity miracle” to hit the target.

“Two stubborn obstacles stand in his way,” The Wall Street Journal reported. “The work force isn’t producing enough new workers, and the productivity of those working isn’t growing fast enough,” WSJ.com reported.

“In the long term, an economy can’t expand faster than the combined growth rates of its working population and their output per hour. That combined number, in many economists’ projections for the next decade, is about 1.8%. This is also the long-run growth rate projected for the economy by Federal Reserve officials,” the Journal reported.

“Mr. Trump’s advisers say their policies can deliver 3% to 4% growth year after year, the kind of prosperity the U.S. saw during the 1980s and