WASHINGTON – Federal Reserve Chairman Ben S. Bernanke sought to reassure lawmakers and the nation that the central bank stood ready to spring into action if the economy stumbled further as the deadline looms on the nation’s debt limit, Europe’s financial problems worsen and U.S. job growth stagnates.

The Fed chief’s remarks to Congress came hours before Moody’s Investors Service Inc. put its top rating of U.S. debt on review for possible downgrade, an action Moody’s previously said it would take in mid-July if there was no significant movement on raising the debt ceiling.

Bernanke’s testimony in his semiannual report to Congress on the economy and monetary policy gave an immediate lift to anxious investors grappling with widespread uncertainty. But most of the gains dissipated by the end of trading Wednesday. And Moody’s statement could unnerve financial markets further.

Analysts said that, while Bernanke left the door open to further monetary stimulus, including another round of bond purchases, it would take a significant deterioration in the economy and the job market for the central bank to act. And Bernanke suggested he did not consider that a likely scenario.

In his semiannual report to Congress on the economy and monetary policy, Bernanke stuck to the view that temporary factors were behind the recent slowdown in the recovery and that the economy would pick up speed in the coming months. The economy in the first half of this year likely grew at an anemic rate of 2 percent or less after expanding by nearly 3 percent in the second half of last year.

“The apparent stabilization in the prices of oil and other commodities should ease the pressure on household budgets,” Bernanke said, adding that the economy also figures to get a boost this summer as car manufacturers step up production after cutting back because of disruptions from Japan’s earthquake and tsunami in March.

“The anticipated pickups in economic activity and job creation, together with the expected easing of price pressures, should bolster real household income, confidence and spending in the medium run,” he told the House Financial Services Committee.

Yet the Fed, as well as many private economists, repeatedly has overestimated future growth – and some think Bernanke did so again Wednesday.

“He’s betting that factors slowing the economy are transitory. That’s his hope,” said Bernard Baumohl, chief global economist at the Economic Outlook Group. But Baumohl sees fuel and food prices remaining relatively high, reflecting long-term geopolitical instability in the Middle East and continued high demand from developing countries such as China. “I believe there is a new normal,” he said.

Bernanke did cite a number of head winds to economic growth, including the depressed housing market, limited credit for some consumers and small businesses, and the belt-tightening at all levels of government.

The Fed chairman also said he expected no quick improvement in the stubbornly weak job market. The nation’s unemployment rate, at 8.8 percent in March, has bounced up in subsequent months, to 9.2 percent in June. And job creation, which had accelerated earlier this year, ground to a near halt in the past two months.

“The jobless rate will decline – albeit only slowly – toward its longer-term normal level,” he said.

The latest forecast from Bernanke and his colleagues at the Fed, which they released three weeks ago, predicted that the unemployment rate would remain near 9 percent in the fourth quarter, about 8 percent around election time next year and in the range of 7 percent to 7.5 percent at the end of 2013.

If the jobless rate continues to climb closer to 10 percent, analysts say, it likely would trigger the Fed to take action with additional monetary stimulus. So would worries over deflation, a broad decline in wages and prices.

But with Fed officials themselves divided on whether further stimulus is needed or would be helpful, the bar would be high. The central bank last month completed a $600 billion program to buy U.S. Treasury bonds to hold down rates, but it’s unclear how effective the measure was in boosting growth. While it may have helped avert deflation and boost the stock market, many economists are concerned that the billions of dollars injected into the financial system will lead to spiraling inflation down the road.

In questioning Bernanke on Wednesday, lawmakers focused largely on the current debt-limit battle and the problems of weak job creation.

The Fed chairman restated that Congress needs to raise the debt ceiling in time and develop a budget that would narrow the deficit over the long haul but not make drastic, immediate cuts that could hurt the recovery.

Bernanke painted a grim picture should the nation fail to meet the deadline and be forced to hold back payments to Social Security beneficiaries, something President Barack Obama said Tuesday was possible if the current impasse is not broken.

“The arithmetic is very simple,” he said. “The revenue that we get in from taxes is both irregular and much less than the current rate of spending” – on the order of about 40 percent.

“The assumption is that as long as possible the Treasury would want to try to make payments on the principal and interest of the government debt, because failure to do that would certainly throw the financial system into enormous disarray and have major impacts on the global economy,” Bernanke said.

But even if the nation doesn’t default on its debt to U.S. Treasury bondholders, he said, failure to meet Medicare, Social Security and other obligations to its citizens could have a devastating effect.

Bernanke noted that the current debt woes in Europe starkly illustrate what can happen when investors lose confidence in a nation’s finances. The Greek debt crisis most recently has spread to Italy, jolting its financial markets and pushing up its borrowing costs.

The U.S. has long supported its deficit spending by issuing Treasury debt, which remains the safe-haven investment for the globe.

“It’s possible that simply defaulting on our obligations to our citizens might be enough to create a downgrade in credit ratings and higher interest rates for us, which would be counterproductive, of course, since it makes the deficit worse,” he said.

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