Geithner is a protege of Summers' and of former Clinton administration Treasury chief Robert E. Rubin.
Geithner worked with Paulson and Federal Reserve Chairman Ben S. Bernanke on the government-engineered sale of Bear Stearns Cos., the bailout of American International Group Inc. and the decision not to prop up Lehman Bros. Holdings Inc.
Born 14 days after Obama, Geithner would be one of the youngest Treasury secretaries in U.S. history.
News of Obama's choice leaked just as he began facing criticism for not moving quickly enough to show Wall Street how he planned to address the crisis. Proponents of naming a team now said Obama should show that appointees would have time to prepare to act as soon as he assumed the powers of the presidency Jan. 20.
"This is all about confidence. It's going to get worse. Fear is going to take over," former General Electric Co. Chief Executive Jack Welch said on financial news channel CNBC. "We have a new president, and the fastest we can get the policies out there that tell us where we are going to go and what this administration is going to do, the better off we're going to be."
Other probable members of Obama's economic team are New Mexico Gov. Bill Richardson as Commerce secretary and Congressional Budget Office Director Peter R. Orszag as head of the White House Office of Management and Budget, according to people knowledgeable about the decision-making process.
Before becoming head of the New York Fed in 2003, Geithner was an official with the International Monetary Fund. He also spent 13 years at the Treasury Department beginning in 1988, serving under three presidents. At the agency, Geithner rose to undersecretary for international affairs, where he worked under Rubin, then Summers, from 1999 to 2001.
His ascent began with a mid-1980s stint at Kissinger Associates, the high-powered consulting firm of former Nixon administration Secretary of State Henry Kissinger, and then at Treasury in Washington during the late 1980s and early 1990s.
But his big break came in the second half of the 1990s, when, as an assistant financial attache at the U.S. Embassy in Tokyo, he wrote what was widely considered a brilliant analysis of the South Korean financial crisis.
The document drew the attention of both Rubin and Summers. They elevated the then-38-year-old Geithner to Treasury undersecretary for international affairs during the final years of Bill Clinton's term in the White House.
