President-elect Barack Obama said a "bold" stimulus plan is needed to pull the US economy out of recession but would not provide a dollar amount for the package Friday.

Obama has proposed an ambitious stimulus plan to create 2.5 million jobs through massive investments in infrastructure which some estimate could cost up to a trillion dollars.

"I won't give you a number, because we are still making these evaluations," Obama said at a press conference.

"What we've seen, in terms of the evaluation of economists from across the political spectrum, is that we're going to have to be bold when it comes to our economic recovery package."

Obama said economists on the left and right had told him that without a big stimulus package, "you could see the economy continuing to decline at a pretty rapid clip."

"That is not acceptable to me. I don't think it is acceptable to the American people," he said.

Obama expressed confidence in his ability to steer the country out of recession but warned a solution to the "daunting" challenges he will inherit when he takes office on January 20 will not come quickly.

"It will take longer than any of us would like -- years, not months. It will get worse before it gets better," Obama said.

"But it will get better if we are willing to act boldly and swiftly, and that is what we will do when I am president of the United States."

While he has no intention of spending taxpayer dollars "lightly," Obama admitted the plan "is going to cost a significant amount of money on the front end."

But he said the money will be more than just a short-term stimulus package to help weather the current economic downturn.

Obama said if he manages to "do this right" he will also lay the groundwork for long-term economic growth by transforming how the country consumes energy, investing in education, improving infrastructure, and reducing health care costs.

He also pledged to get mid-term and long-term budgets "under control" and make sure money isn't wasted on pork barrel projects, but cautioned that the country would have faced a colossal budget deficit even if a stimulus package was not required.