As U.S. lawmakers were voting on a giant economic recovery plan, President Barack Obama again emphasized the many challenges facing the nation's economy. 

President Obama said 3.6 million jobs have been lost since the recession began, and many big companies are under pressure from falling revenues and unavailable credit.

But he said the $789 billion economic stimulus plan should help, and he praised the "spirited debate" about the bill in Congress.

"Not everybody has shared the same view of how we should move forward, and at times our discussions have been contentious.  But that is a good thing from my perspective," he said.

Mr. Obama told the leaders of some of America's biggest companies that the recovery plan is only the first step, and that more patience will be needed.

"Now, passing this plan is a critical step, but as important as it is, it is only the beginning of what, I think all of you understand, is going to be a long and difficult process of turning our economy around," he said.

The president said the next steps should include implementing the restructured $700 billion financial industry bailout program, reforming financial industry regulation and writing what he called a "responsible" federal budget.  He is scheduled to unveil a housing initiative next week.

Mr. Obama said the economic crisis is also an opportunity to take strong action to set the nation's economic course for decades to come.

"We have a once-in-a-generation chance to act boldly and turn adversity into opportunity, and to use this crisis as a chance to transform our economy for the 21st century," he said.

Underscoring Mr. Obama's concerns, a new study found U.S. consumers are becoming more worried about their economic situation.  The University of Michigan's index of consumer sentiment approached a record low this month, dropping five percentage points.  Consumer spending accounts for about two-thirds of the U.S. economy.

The president said the massive economic recovery legislation will help increase consumer spending, make necessary investments for lasting growth and prosperity, and save or create more than 3.5 million jobs. 

The compromise plan includes more than $311 billion in spending on infrastructure, health care, energy and aid for low-income Americans.