Employers probably hired 160,000 workers in January, after a 155,000 increase in December, based on Bloomberg News survey of economists before the Labor Department reports the figures on Feb. 1.

In the first round of purchases, begun in 2008, the Fed bought $1.4 trillion of housing debt and $300 billion of Treasuries. In the second round, beginning in November 2010, the Fed bought $600 billion of Treasuries.

Mortgage Bonds

In the current round, the Fed’s total purchases will be split between $600 billion of mortgage-backed securities and $540 billion of Treasuries, according to the median estimates of economists in the survey.

Asked what would prompt the Fed to halt its bond buying, 63 percent of economists said the central bank will act in response to substantial improvement in the labor market.

Only 13 percent said the Fed will end its purchases because of accelerating inflation or a rise in inflation expectations.

Inflation for the 12 months ending in November was 1.4 percent, according to the Fed’s preferred gauge. That’s below the central bank’s longer-run target of 2 percent. Investors expect inflation of 2.24 percent over the next five years, compared with 2.1 percent when the FOMC met Dec. 11-12, as measured by the spread between Treasury Inflation Protected Securities and nominal bonds.

At the FOMC’s meeting last month, participants differed over how long the bond purchases should last. Fed officials who provided estimates were “approximately evenly divided” between those who said it would be appropriate to end the purchases around mid-2013 and those who said they should continue beyond that date, according to minutes of the gathering.

Committee Efforts

A number of policy makers are concerned the size of the Fed’s holdings “could complicate the committee’s efforts to eventually withdraw monetary policy accommodation,” according to the minutes.