President-elect Barack Obama today will launch his campaign for a new economic stimulus package with grave warnings of the consequences of inaction, saying the economy could fall “$1 trillion short,” face double-digit unemployment and a recession that could last for years.

“We could lose a generation of potential and promise, as more young Americans are forced to forgo dreams of college or the chance to train for the jobs of the future,” Obama plans to say, according to prepared remarks released by his office. “And our nation could lose the competitive edge that has served as a foundation for our strength and standing in the world.”

Obama is scheduled to speak late this morning at George Mason University in Fairfax, Va. His appearance will mark yet another milestone in what has effectively become the domestic policy presidency of a man who is not yet president.

In his remarks, Obama promises legitimate Congressional debate on the measure while demanding immediate action. “We should have an open and honest discussion about this recovery plan in the days ahead, but I urge Congress to move as quickly as possible on behalf of the American people,” he says. “For every day we wait or point fingers or drag our feet, more Americans will lose their jobs.”

Obama acknowledges that the cost of the plan is “considerable,” but argues repeatedly that only the government can bail out the economy in its dire condition. Obama asserts that the initiative “is not just another public works program,” noting that it will invest in “priorities like energy and education, health care and a new infrastructure that are necessary to keep us strong and competitive in the 21st century.” The president-elect argues that the “overwhelming majority of jobs” will be created in the private sector, while adding that the proposal would “save the public sector jobs of teachers, cops, firefighters and others who provide vital services.”

The proposal, Obama suggests, also will revamp the nation’s financial regulatory system and take further steps to “get credit flowing again.”