WASHINGTON - Barack Obama's transition team is said to be in a state of high anxiety these days, and not just about the logistics of bringing their man and his closest advisers to the White House in a month.

Inauguration headaches and cabinet appointments are mere piffle compared to the gaping maw of the economic meltdown, and growing fears that the recession is going to get a lot worse before it gets better.

Double-digit unemployment. Deflation. Plummeting demand for goods and services. Mammoth, stubborn deficits.

This is the stuff of nightmares for the president-elect and his team, and the reason why they're working hard on an economic stimulus plan now pegged at a staggering US$1 trillion.

Obama was elected in November on a wave of hope and a desire for change, and yet he's confronting the most dire and constraining set of economic circumstances since Franklin Delano Roosevelt took office in the midst of the Great Depression.

"We're in some uncharted territory," John Geer, an author and political science professor at Vanderbilt University in Nashville, Tenn., said in a recent interview.

"Economists don't really have a handle on it and we keep moving from one solution to another."

Christina Romer, who will lead Obama's Council of Economic Advisers, is surveying the country's leading economists, trying to build political consensus around the $1 trillion price tag -- significantly more than the $600 billion that's being publicly bandied about -- before the package is presented to Congress in early January.

The Wall Street Journal has reported that aides consider $600 billion over two years "a very low-end estimate" and have instead almost doubled it.

And yet days after the Journal story caused a buzz in Washington, House Speaker Nancy Pelosi said the House would pass a $600-billion stimulus package before Obama's inauguration, with no mention of the $1 trillion figure. A new Congress, with larger Democratic majorities, gets sworn in on Jan. 6.

However high the final price tag soars, America seems poised to become a literal construction zone for the next few years under Obama's plan.

In addition to an initial tax cut, there will be a massive infusion of cash for roads, bridges, water systems, school repair, increased broadband access, promoting health-care information technology, improving energy efficiency in buildings, renewable-energy projects and assisting struggling state and local governments.

But even if the plan succeeds in turning the U.S. economy around, a worldwide recession could cause other problems for Obama.

It could present his administration, for example, with its first foreign policy crisis should the bottoms fall out of the vulnerable economies of unstable nations like Pakistan or the Philippines.

Social unrest is sure to follow in those regions in the event of an economic collapse, and this time around the U.S. will have no money to bail out any of its friends or allies.

On top of everything else, the president-elect must also begin extricating the United States from the unpopular war in Iraq while also addressing global warming and America's ever-increasing dependence on dirty and uncertain sources of energy.

In terms of the environment, anyway, Obama says he's determined to do whatever's necessary to address the problem despite the free-falling economy.

"This time must be different," Obama said recently. "This will be a leading priority of my presidency and a defining test of our time. We cannot accept complacency, nor accept any more broken promises."

Geer said he agrees that Obama is coming into power with the most unenviable set of circumstances of any president in recent memory.

"These are amazing challenges for Obama, but they also present amazing opportunities," he said.

"The best presidents have all been great not just because of their skills, but because they've had the opportunity to be great, and Obama will have a lot of free hand and a lot of good will."

Geer cautioned, however, that the American public would not grant Obama an indefinite honeymoon period. They will need to see results before the mid-term elections in 2010.

"If he can just begin to deal with a little bit of the Iraq situation and gets the economy straightened out, the public will allow him to do what he needs to do to get that done -- even if, in fact, it's not consistent with some of his promises and even if it causes them some short-term pain," he said.

"But at a certain point, they all become his problems, and they become the problems of the Democrats, and the Republicans will be around to remind people of that fact."

Cal Jillson, author of "Pursuing the American Dream: Opportunity and Exclusion Over Four Centuries," agreed that most great presidents began their years in the White House confronting serious difficulties.

But others have failed miserably in the face of adversity, Jillson pointed out, citing James Buchanan as one example of a commander-in-chief who buried his head in the sand as the Civil War approached and went down in history as a resounding failure.

"Insurmountable problems have remained insurmountable for some presidents," Jillson said.

"Presidents have been crushed by problems as well as being famous for having solved them. For every Franklin Roosevelt you've got a Herbert Hoover, for every Abraham Lincoln, you have a James Buchanan."