As skeptics question the size and direction of his economic stimulus plan, President-elect Barack Obama warned Thursday that “a bad situation could become dramatically worse” unless Congress acts swiftly.

“I don’t believe it’s too late to change course, but it will be if we don’t take dramatic action as soon as possible,” he said in remarks at George Mason University. “If nothing is done, this recession could linger for years. The unemployment rate could reach double digits. Our economy could fall $1 trillion short of its full capacity, which translates into more than $12,000 in lost income for a family of four.”

On Capitol Hill, House Speaker Nancy Pelosi said she wants to get the plan through her chamber by the end of January and see it on Obama’s desk by mid-February. She promised committee markups of the plan, as well as a House-Senate conference committee, reflecting Obama’s call for an inclusive process.

Obama’s aides have been meeting with key Democratic leaders on Capitol Hill to put together a package of roughly $775 billion they are calling the American Recovery and Reinvestment Plan. Intensify his public sale of the plan, Obama vowed it would create at least 3 million jobs over the next few years, adding that 95 percent of American families would benefit from a $1,000 per family tax cut.

He discussed some other specific goals, including modernizing 75 percent of federal buildings and improving the energy efficiency of 2 million homes to save consumers and taxpayers billions on energy bills.

He also promised creation of jobs building solar panels and wind turbines, constructing fuel-efficient cars and buildings and developing new energy technologies.

The plan would double the production of alternative energy within three years, Obama said.

Adding details to his pledge to modernize health record keeping, he set a deadline of five years for having all medical records computerized.

Making Case for Bold Intervention

Obama answered critics who have raised questions about the rapidly growing government involvement in the economy.

“It is true that we cannot depend on government alone to create jobs or long-term growth,” Obama said, “but at this particular moment, only government can provide the short-term boost necessary to lift us from a recession this deep and severe. Only government can break the vicious cycles that are crippling our economy — where a lack of spending leads to lost jobs which leads to even less spending; where an inability to lend and borrow stops growth and leads to even less credit.”

The challenge of crafting an effective stimulus package has been intensified by Wednesday’s Congressional Budget Office projection that the federal budget deficit will hit a staggering $1.2 trillion this fiscal year, even before the cost of the stimulus package is figured in.

“There is no doubt that the cost of this plan will be considerable,” Obama said. “It will certainly add to the budget deficit in the short-term. But equally certain are the consequences of doing too little or nothing at all, for that will lead to an even greater deficit of jobs, incomes, and confidence in our economy.”