Economist Perry Mehrling tells the New York Times that Mr. Bernanke was being cautious about not overstepping the Fed’s role. “Probably he would prefer fiscal easing over quantitative easing, but that decision is ultimately a political one,” he said. 

"Perry Mehrling, a Barnard College economist who has written a forthcoming book on Fed policy called The New Lombard Street, is more skeptical. He says the Fed's first asset-buying program made sense because it was focused on mortgage-backed securities, for which there was scant private demand after the housing collapse. In contrast, he says, there's no lack of private demand for Treasuries, so purchases are 'unlikely to have much positive effect,'" writes Businessweek.