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President Barack Obama announces his choice of White House Chief of Staff Jack Lew as the next Treasury Secretary in the East Room of the White House on January 10, 2013 in Washington, DC.

President Barack Obama nominated Jack Lew, his current chief of staff, to be the next Secretary of the Treasury Thursday, elevating his wonky former budget director to a position at the center of fights over the nation's deficit and spending. 

"Jack knows that every number on a page, every dollar we budget, every decision we make, has to be an expression of who we wish to be as a nation, our values," the president said at the White House announcement of Lew's nomination.

Related: Team Obama trips on cabinet shuffle

The president did not indicate who will replace Lew. The leading candidates for the next chief of staff are former Biden chief of staff Ron Klain and Deputy National Security Adviser Denis McDonough. 

"I don't want to see him go, because it's working out really well for me to have him in the White House," Obama said of his departing chief. "But my loss will be the nation's gain."

Lew, known as a tough negotiator who clashed with House Republican aides during last year's debt ceiling negotiations, previously served as the director of the Office of Management and Budget under both Obama and former President Bill Clinton. 

Lew will replace outgoing secretary Tim Geithner, who took the post at the start of Obama's first term, when financial markets were still roiling from the 2008 meltdown. 

"I couldn't blame Tim when he told me he wasn't the right guy for the job," Obama joked. 

Praising Geithner for his handling of the economy throughout his four year tenure, Obama noted that he pleaded with Geithner to stay on despite his onetime desire to leave before the end of Obama's first term. 

"When the history books are written, Tim Geithner's going to go down as one of our finest Secretaries of the Treasury," Obama said to sustained applause from the audience at the White House. 

In remarks, Lew joked about his famously loopy signature, saying that he and Geithner share "a common challenge with penmanship." (The Treasury Secretary's signature appears on all paper currency.) 

Obama wryly responded that, while he considered rescinding Lew's nomination over his sloppy signature, the new pick had promised to work to make at least one letter legible so as to "not debase our currency." 

Critics have pointed out that Lew, who served as chief operating officer of Citigroup Alternative Investments in 2008 before coming to OMB, benefited from that unit's investments in anticipation of the housing market collapse.

That's likely to be discussed at his confirmation hearings, and Republicans like Senate Budget Committee ranking member Sen. Jeff Sessions have already voiced opposition to Lew's selection for the post. 

On Thursday, Chamber of Commerce President Tom Donohue described the new Treasury pick as an experienced veteran of fiscal debates. 

"Jack's been around for a long time," he said. "He's a tough dude." 

For more about Lew's background, click here to read NBC's coverage from yesterday. 

NBC's Bob Costantini contributed to this report. 

The New York Times: “With his choice of Jacob J. Lew to be the secretary of Treasury, President Obama on Thursday will complete the transformation of his economic team from the big-name economists and financial firefighters hired four years ago to budget negotiators ready for the next fiscal fights in Congress. If confirmed by the Senate, the 57-year-old Mr. Lew — Mr. Obama’s current chief of staff and former budget director — would become the president’s second Treasury secretary, succeeding Timothy F. Geithner, who was the last remaining principal from the original economic team that took office at the height of the global crisis in January 2009.”

“The White House is working with its allies on a well-financed campaign in Washington and around the country to shift public opinion toward stricter gun laws and provide political cover to lawmakers who end up voting for an assault-weapons ban or other restrictions on firearms,” the Washington Post writes.

The Washington Post’s Greg Sargent: “The powerful Financial Services Roundtable — which is headed by former GOP presidential candidate Tim Pawlenty and represents nearly 100 of the largest financial service firms in the country — is set to increase pressure on Congress to raise the debt limit, warning that failure to do so will make the markets go ‘haywire.’ ‘We are in favor of raising it, and we will be encouraging policy makers to increase it,’ Scott Talbott, the senior vice president for public policy for the Financial Services Roundtable, told me today. He added that the group was gearing up to communicate the demand for action to Congress, an effort that could include sending letters to every member. ‘We will communicate with the entire Congress,’ he said.”

And in the New Republic, Noam Scheiber argues that Obama – potentially – could have gotten a better deal from Republicans in the fiscal-cliff talks. “Because it turns out Obama made a critical if underappreciated mistake in the final hours of the back and forth: sending Joe Biden to haggle with Senate Republican leader Mitch McConnell once McConnell's talks with his Democratic counterpart, Harry Reid, had broken down.”

More: “From my after-the-fact discussions with Democratic aides in the House and Senate leadership, it’s clear that Reid had a plan for resolving the cliff and considered the breakdown of his talks with McConnell very much a part of it. By involving Biden, Obama undercut Reid and signaled that he wanted a deal so badly he was unwilling to leave anything to chance, even when the odds overwhelmingly favored him. It suggested that even if Obama plays his cards exceedingly well in the run-up to the debt-limit showdown, he could still come away with a worse deal than he deserves because of his willingness to make concessions in the closing moments.”

Chip Somodevilla / Getty Images file

President Obama is expected nominate Jack Lew, left, as the Treasury Secretary, replacing Timothy Geithner, right, pictured here during a press conference Sept. 19, 2011 in Washington, D.C.

Updated 12:15 p.m. ET -- President Barack Obama will announce current White House Chief of Staff Jack Lew as his pick to be the next Secretary of the Treasury, CNBC's John Harwood confirmed Wednesday. The announcement could come as early as Thursday.

Lew, who previously served as budget director under Obama and President Bill Clinton, has long been considered the frontrunner to replace departing Secretary Timothy Geithner, the last remaining member of Obama's first-term economic team.

A former investment banker and Capitol Hill aide, Lew was instrumental in crafting the August 2011 debt deal that created the automatic tax increases and spending cuts narrowly avoided in the New Year's "fiscal cliff" agreement.

Those negotiations didn't make Lew a hero to congressional Republicans, who were reportedly irked by his style. Journalist Bob Woodward wrote in his book "The Price of Politics" that top aides to House Speaker John Boehner found Lew "disrespectful and dismissive" and "obnoxious" during the talks.

But, despite the bruising fight set up by the cliff built in the August talks, Lew's strategy ultimately helped set up what observers have deemed a political victory for Obama early in 2013.

A 57-year-old native of New York City, Lew's long familiarity with Capitol Hill began when he took a job as a legislative aide in 1973. He went on to serve for nine years as chief domestic policy adviser to House Speaker Tip O'Neill.

While Lew's announcement is expected soon, per CNBC's Harwood, it's not clear that the president has settled on his new choice for chief of staff.

Deputy National Security Adviser Denis McDonough and former Biden chief of staff Ron Klain are both seen as potential Lew replacements.

Related content:

Jack Lew's loopy signature may have to go

Earlier today, Bloomberg News reported that Treasury Secretary Tim Geithner is planning to leave the Obama administration by the end of January, even if the White House and Congress haven't yet reached a deal on the debt ceiling by then.

In response to a question from First Read about the article, a Treasury spokesperson says that Geithner has previously stated he plans to stay "until around the inauguration" -- so late January.

"Secretary Geithner has previously stated that he plans to be at Treasury until around the inauguration," the spokesperson said. "We do not plan to make any further announcements about the timing of the Secretary's departure until after his successor is named."

Geithner, 51, is the only remaining original member of Obama's cabinet and has been an instrumental figure in the administration's handling of the bank bailouts and economic recovery efforts in the wake of the 2008 financial crisis. 

Prior to joining the Obama administration, Geithner served as the president and CEO of the Federal Reserve Bank of New York. He first joined the Treasury department in 1988 and served in various roles under three separate administrations.  

One possible contender for the job after Geithner's departure is current White House Chief of Staff Jack Lew, who previously served as the Director of the Office of Management and Budget.

NBC's Carrie Dann contributed to this report.