Federal Reserve Bank of St. Louis President James Bullard said the central bank should resume purchases of Treasury securities if the economy slows and prices fall rather than maintain a pledge to keep rates near zero.

“The U.S. is closer to a Japanese-style outcome today than at any time in recent history,” Bullard said, warning in a research paper released today about the possibility of deflation. “A better policy response to a negative shock is to expand the quantitative easing program through the purchase of Treasury securities.”

Fed policy makers are considering what actions to take, if any, to spur growth and reduce unemployment should the economy weaken further. Chairman Ben S. Bernanke told Congress last week the Fed could use communication to plot the path of interest rates, cut the rate it pays banks on excess reserves or purchase more bonds.