Initial reactions from the business and financial sectors, however, were far more positive.
"One of the realities of Mr. Lew's appointment is the challenges we face in the country right now — the cliffs we have in front of us," said Thomas Donohue, the president and CEO of the U.S. Chamber of Commerce. "I think Jack is a very experienced fellow on the issues of debt, deficits and budgets."
Donohue called Lew a "skilled operative," a "vigorous and strong person" and a "tough dude."
Rob Nichols, the president and CEO of the Financial Services Forum, a major banking industry group, said: "Given his experience in the government and private sector, Mr. Lew is well-suited for the job especially at a time when Washington must come together to address our debt situation and put our nation on a long-term fiscally sustainable path."
Lew's nomination is the fourth major personnel change in the administration since Obama's re-election. Obama tapped Sen. John Kerry, D-Mass., to become secretary of state, former Republican Sen. Chuck Hagel of Nebraska as defense secretary and White House counterterrorism adviser John Brennan for the CIA's top job.
Geithner is expected to remain at Treasury through Jan. 25.
While Lew does not have the extensive Wall Street experience of past treasury secretaries, many analysts said that his experience dealing with budget issues should make up for that.
"He knows the federal budget in gory detail and he has a lot of experience working with Congress," said Mark Zandi, chief economist at Moody's Analytics. "Those are two big plusses for any treasury secretary. The next couple of years will be about getting our fiscal house in order and there is no better person to do that than Mr. Lew."
Lew, an Orthodox Jew who eschews work on Saturdays, is the picture of a policy bookworm with his glasses and neatly parted shock of hair. It's a look that has defined him since his days working for Tip O'Neill in room H-209 in the Capitol, sitting next to Chris Matthews, then a top O'Neill aide and now the garrulous MSNBC television host.
Matthews, a fan of Lew's, marveled that Lew's looks and his "Maginot Line hairline" remained the same from their days on the Hill.
"I watched that part this morning, and it hasn't changed," he said.
Now 57, Lew was in his mid- to late-20s while working for O'Neill and had a hand in negotiations between the speaker and President Ronald Reagan that led to a bipartisan agreement to extend the solvency of Social Security.
"Very young guy, just a smart guy," Matthews recalled Thursday. "I looked like the door keeper, he was the smart guy in the corner."
Associated Press writer Martin Crutsinger contributed to this report.
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