President Barack Obama will nominate Jack Lew as Treasury secretary as early as Thursday, making him his point man in the coming battle over the debt ceiling, a source familiar with the process told CNBC.
In another move, Labor Secretary Hilda Solis announced plans Wednesday to step down from the position she assumed in 2009.
Lew, the White House chief of staff and former director of the Office of Management and Budget, would succeed Timothy Geithner, who has been planning to step down.
A source told CNBC that Deputy National Security Adviser Denis McDonough was a leading candidate to succeed Lew as chief of staff.
Lew's expected appointment would be subject to confirmation by the Democratic-controlled Senate.