(AP) - President-elect Barack Obama says that withoutbig-time federal stimulus dollars now, the nation's recession couldgo on for years. In a speech set to be delivered today at Virginia's George MasonUniversity, outside Washington, Obama is making his highest-profilecase yet for a stimulus plan. Obama says there's still time to change course but without"dramatic action as soon as possible," it may become too late. Obama says a worst-case scenario could include double-digitunemployment and $1 trillion in lost economic activity that recallsthe days of the Great Depression. It's the fourth day in a row that Obama has made a pitch for ahuge infusion of taxpayer dollars to revive the sinking economy.