Wearing a traditional Peruvian poncho, President George W. Bush gestures as Japan’s Prime Minister Taro Aso stands below before the official group photo of the 16th summit of the Asian Pacific Economic Cooperation, APEC, in Lima.

CHICAGO (AP) — Pushing the calendar, and maybe his luck, President-elect Barack Obama is urging rapid approval of a massive economic stimulus package meant to calm turbulent financial markets.

He will not be president for another eight weeks, and the politically safer route might be to lie low as President George W. Bush finishes his rocky term. But in announcing his economic team Monday at a White House-style news conference, Obama has chosen to use the bully pulpit even before he assumes the office, gambling that he can soften the economy’s fall while he continues to fill out the rest of his cabinet.

“The truth is, we do not have a minute to waste. These extraordinary stresses on our financial system require extraordinary policy responses,” Obama said, introducing New York Federal Reserve Bank president Timothy Geithner as his treasury secretary and Lawrence Summers, a former treasury secretary under President Bill Clinton, to lead the National Economic Council.

Obama has said repeatedly there can be only one president at a time, and has kept a relatively low public profile as Bush and Treasury Secretary Henry Paulson have tried to address the mortgage and credit crisis that threaten a deep global recession. That changed at his news conference Monday, when the president-elect pressed for passage of a multibillion-dollar stimulus plan aimed at creating jobs, easing the home foreclosure crisis and rescuing the struggling auto industry.

Doug Astolfi, a presidential historian at Florida’s St. Leo University, said that because of the recent stock market plunge Obama had little choice but to step forward.

“Had he not gotten involved, the potential for really disastrous shifts in the economy were all there,” Astolfi said, adding that until his inauguration Obama is still insulated from blame if things get worse.

“He can key in a team and push for policies. But if bad things happen he’s protected from most criticism because it’s the fault of the people who are still there,” Astolfi said.

To be sure, Obama refused to specify how much the proposal would cost or how he would pay for it, even as Democratic allies in Congress have predicted a price tag of as much as $700 billion. “It’s going to be costly,” he warned, noting that both conservative and liberal economists agree on the need for such unprecedented intervention.

Obama planned another news conference Tuesday to introduce Peter Orszag, the Congressional Budget Office director and the president-elect’s pick to be his budget director. He also was set to outline what he described as “meaningful cuts and sacrifices” to help ease the financial crunch.

By stepping out so forcefully, Obama signaled he was not following the example of another Democratic president, Franklin Delano Roosevelt, who was elected in 1932 during another period of economic calamity. Roosevelt refused to cooperate during the transition with his vanquished predecessor, Republican Herbert Hoover, waiting instead to tackle the crisis after he was sworn in as president.

Obama said Monday he had spoken to Bush and Federal Reserve Chairman Ben Bernanke about the proposed government bailout of Citigroup Inc.

“My commitment is to do what’s required so that our financial system works and credit flows. President Bush has indicated that he has the same approach, the same attitude,” Obama said.

But Obama stepped symbolically away from Bush as well, stressing repeatedly that his stimulus plan was aimed at middle-class wage earners, not just big financial institutions. It was an implicit reminder that many of Bush’s economic policies have favored the wealthy.

“We cannot have a thriving Wall Street without a thriving Main Street, that in this country we rise or fall as one nation, as one people,” Obama said, promising to make good on his pledge to bring tax relief to families earning less than $250,000 a year.

Obama also used Monday’s news conference to lob a warning at the Big Three automakers — and indirectly their powerful union, the United Auto Workers — who have pressed Congress for $25 billion in government loans to wrest them from the brink of bankruptcy.

Obama has urged help for the auto industry but cautioned that Ford Motor Co., Chrysler LLC and General Motors Corp. must do a better job of explaining how they plan to reform their business practices.

“We can’t just write a blank check to the auto industry. Taxpayers can’t be expected to pony up more money for an auto industry that has been resistant to change,” he said.

Jack Pitney, a government professor at California’s Claremont McKenna College, said Obama was showing “equal parts assertiveness and reassurance” by his decision to step forward.

“He’s not trying to usurp the president’s authority,” Pitney said, “but he’s trying to prepare the groundwork for the moment he takes the oath.”