Washington ? President-elect Barack Obama sought to assert his authority over the country’s deepening financial crisis Monday, unveiling his economic team and making it clear that he will not wait until Inauguration Day to set his plans for recovery in motion.

Declaring that America is caught in a “vicious cycle” affecting both Wall Street and Main Street, Obama said his advisers will begin work immediately toward passage of a stimulus package large enough to “jolt” the faltering economy back into shape.

Timothy Geithner, president of the New York Federal Reserve Bank, will lead that effort as Treasury secretary, along with Lawrence Summers, the former president of Harvard University and Geithner’s mentor for the past decade, who was named to lead the National Economic Council. Berkeley professor Christina Romer will head the Council of Economic Advisers, which advises the president on domestic and international economic matters.

“And that work starts today, because the truth is, we don’t have a minute to waste,” Obama told reporters at a news conference in Chicago, where he was joined by his new team. “With our economy in distress, we cannot hesitate and we cannot delay. Our families can’t afford to keep on waiting and hoping for a solution.”

Geithner, 47, will coordinate the Obama administration’s response to the faltering economy, serving as the primary architect of the stimulus package. While Geithner will assume broad authority to direct hundreds of billions of dollars in government funds from his post at Treasury, Summers is expected to have Obama’s ear as the head of the NEC and could play an important role in synthesizing the economic advice the new president receives.

Obama has maintained a low profile in the weeks since his election victory, resigning his Senate seat and quietly vetting his Cabinet as Congress and the White House haggled over proposals for a stimulus package and a bailout of the automobile industry, neither of which came to pass.

But in his second news conference since becoming president-elect, Obama appeared much more willing to assume ownership of the current turmoil, easing away from his emphatic statement that America has only “one president at a time” and signaling a shift in the balance of power between the current and incoming administrations as the financial crisis engulfs more banks and threatens millions of jobs.

Obama urged Congress to convene in early January to pass a new stimulus package, with the goal of having it ready for the new president’s signature immediately after he is sworn in on Jan. 20. And he made it clear that he expects Bush’s economic team to work with his own during the transition.

Obama was briefed by Bush Monday as the government agreed to protect Citigroup from billions in potential losses from troubled assets. The president-elect said the news about Citigroup added to the evidence that the country faces “an economic crisis of historic proportions.”