WASHINGTON -- President-elect Barack Obama signaled yesterday that he will move aggressively to rescue the plunging economy, demanding swift passage by Congress of a massive two-year spending and tax-cutting program. "We're out with the dithering. We're in with a bang," a top aide said. Obama's plans could put aside his campaign pledge to repeal a Bush tax cut for the wealthy. Those tax cuts might remain in place until they are scheduled to die in 2011, said William M. Daley, an economic adviser. "That looks more likely than not," he said.