Ben S. Bernanke, chairman of the Federal Reserve, speaks at a news conference following the Federal Open Market Committee meeting on June 19. The Fed believes the economy eventually will be strong enough to handle a pullback in stimulus. But a prolonged rise in interest rates for mortgages and other loans would become a key factor in the central bank’s decision. (Pete Marovich/BLOOMBERG)

The Federal Reserve is becoming concerned that the recent spike in interest rates could disrupt the rebound in the housing market and force the central bank to delay plans to scale back its multibillion-dollar economic stimulus.  

The Fed believes the economy eventually will be strong enough to handle a pullback in stimulus, likely in the fourth quarter. But a prolonged rise in interest rates for mortgages and other loans would become a key factor in the central bank’s decision.

 Chairman Ben S. Bernanke said last week that the Fed is monitoring these rates but expressed hope that consumer confidence could offset the increase. Since then, interest rates on 30-year fixed mortgages have gone up at least half a percentage point, a rare jump for such a short time.

The Fed’s $85 billion-a-month bond-buying program is one of the last sources of economic stimulus for the country. Officials have been trying to prepare the markets for its eventual end.  Bernanke said last week that will probably occur in mid-2014, when the unemployment rate is expected to be about 7 percent. 

But the jobless rate is not the only consideration. The Fed is looking for faster economic growth and a pickup in inflation. The government on Wednesday said the economy expanded at an annual rate of 1.8 percent — well below its initial estimate of 2.4 percent. Meanwhile, inflation has fallen to less than 1 percent, about half the Fed’s target rate.

The central bank could also adjust its timetable if the real estate market took a turn for the worse. Officials have repeatedly credited the housing recovery with helping to rebuild Americans’ wealth, boost confidence and support greater spending. A closely watched index of home prices in 20 major cities released Tuesday jumped a record 12 percent in April — when interest rates were falling.

“While other parts of the economy may be sputtering, the housing market continues to show the strength and resilience of the consumer,” said Kim Fraser, senior economist for BBVA Compass.

To be sure, the spike in interest rates may prove temporary. Home buyers could also shrug off the increases, which analysts say do not yet translate into significantly larger monthly mortgage payments. But the Fed will be closely watching the ripple effects through the real estate market, along with other rate-sensitive sectors such as auto sales.

Speaking to reporters last week, Bernanke tried to hedge the timeline for pulling back the Fed’s stimulus. He has repeatedly said that the central bank’s actions will depend on economic data, such as progress in the labor market and the pace of growth. Last week, he said the timeline could also change if “financial conditions are judged to be inconsistent with further progress in the labor market,” he said.

“Our policy is in no way predetermined and will depend on the incoming data and the evolution of the outlook,” Bernanke said during the press conference.

Markets, however, may not have gotten the message. The chairman’s remarks fueled fears that the Fed might wind up raising its target for short-term interest rates sooner than expected. U.S. stock markets plunged 3.5 percent in the days after Bernanke’s remarks. Yields on 10-year Treasury, the benchmark for many interest rates, have jumped to the highest levels in two years.

An unusual rush to sell bonds is driving up the cost of mortgages and other loans. Rates on 30-year fixed mortgages have jumped at least half a percentage point over the past week, said Greg McBride, senior financial analyst at Rates jumped more in recent days than they have over the previous nine months combined, he said.

“It’s rare to see an increase of that magnitude in such a short amount of time,” McBride said.

The central bank itself may be contributing to anxiety in the market. The Fed’s top ranks are made up of a seven-member board of governors and 12 regional bank presidents, and Bernanke has encouraged open debate among them. But opposing viewpoints within the central bank and a multitude of speeches on what the Fed should do — seven officials are scheduled to deliver remarks over the next few days — has been confusing.

In an interview this week, Minneapolis Fed President Narayana Kocherlakota said that lack of clarity is causing investors to overreact.

“The questions about the front end are really questions about the back end,” he said. “What is economically a minor tweak in monetary policy is seen as having big consequences.”

Kocherlakota said the Fed should explicitly leave open the possibility that it will keep buying bonds to stimulate the economy even after the unemployment rate falls to 7 percent. Although he does not hold a seat on the Fed’s influential policy-setting committee this year, he will join the group next year when the central bank is expected to be in the midst of ending the program.

But another top Fed official said the market was simply reacting to the central bank pulling on the reins of the recovery. St. Louis Fed President James Bullard said he disagreed with the decision to announce the plan for ending the central bank’s bond-buying. He said the Fed should have waited for stronger economic data.

“It wasn’t Fed communication,” he said in an interview. “This was tighter policy.”

Apart from its bond-buying program, the central bank has also cut its target interest rate to near zero. It has promised not to raise it at least until the unemployment rate hits 6.5 percent. Bernanke has stressed the Fed could leave the rate unchanged even longer than that, particularly if inflation remains low.