“The current St. Louis Fed forecast for the unemployment rate implies that the 6.5 percent threshold will be crossed in June 2014,” Bullard said in New York.

The Fed last month renewed its pledge to keep borrowing costs low “at least as long” as joblessness exceeds 6.5 percent and if projected inflation won’t go beyond 2.5 percent one or two years in the future.

Editor's Note: Billionaires Dump Stocks. Prepare for the Unthinkable.

Bullard repeated his proposal to adjust the Fed’s $85 billion in monthly bond buying to account for changes in the economic outlook. Fed Chairman Ben S. Bernanke has said the Fed will keep buying bonds until there’s a “substantial” improvement in the labor market, and the Fed hasn’t specified a date for the end of purchases.

“Without an end date, the committee may have to alter the pace of purchases as news arrives concerning U.S. macroeconomic performance,” Bullard said to the Center for Global Economy and Business at New York University’s Stern School of Business.

The Federal Open Market Committee on Jan. 29-30 debated Bullard’s proposal, according to minutes of the meeting. Several participants “emphasized that the committee should be prepared to vary the pace of asset purchases,” the minutes showed.

Dallas Fed President Richard Fisher has also endorsed the idea of “tapering” asset purchases before halting the stimulus to avert a potentially disruptive “cold turkey” end in the buying. The central bank, seeking to stoke growth and bring down 7.9 percent unemployment, has expanded its balance sheet to a record exceeding $3 trillion.

Editor's Note: Billionaires Dump Stocks. Prepare for the Unthinkable.