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President Obama joked about his Chief of Staff Jack Lew's now-famous curly signature as he announced Lew's nomination for Treasury Secretary from the East Room of the White House Thursday.

"I had never noticed Jack's signature," the president said. "And when this was highlighted yesterday in the press, I considered rescinding my offer to appoint him."

The Treasury Secretary's John Hancock is featured on paper currency minted during the time he serves. Lew signs his name with a series of slinky-like curls, leading to speculation of what dollar bills might look like if Lew is confirmed.

The president jokingly said he received a promise from Lew that would ensure the value of paper money.

"Jack assures me that he is going to work to make at least one letter legible in order not debase our currency should he be confirmed as Secretary of the Treasury," Mr. Obama said.

Lew referenced his signature's new-found fame and drew current Treasury Secretary Tim Geithner into the joke.

"You know I thought I knew you pretty well," Lew said of Geithner. "But it was only yesterday that I discovered we both share a common challenge, penmanship."

But it remains to be seen whether Lew's signature will ever appear on the nation's money. He faces a difficult confirmation battle in the U.S. Senate.

The ranking member of the Senate Budget committee, Jeff Sessions (R-Ala.) has voiced strong opposition to Lew's nomination.