The Treasury Department is interviewing Wall Street bankers to advise the government on an IPO of General Motors Co., the most serious sign yet that the government is moving to end its auto-industry ownership, The Wall Street Journal reported.

Among the Wall Street firms vying for the role are Greenhill & Co., Lazard Ltd. and Perella Weinberg Partners, according to people familiar with the meetings. The Treasury department declined to comment.

While an initial public offering is still several months away at the earliest, the investment-banker pitches, known as a "bake-off," held this past week represent the most concrete steps the U.S. has taken to recoup its bailout stake, one of a string of massive cash injections to prop up major U.S. companies during the market meltdown.

The U.S. holds a 61 percent stake in GM after its $50 billion bailout of the automaker last year, which included a 40-day stay in bankruptcy that ended July 10. Under the deal, GM was to directly repay a $6.7 billion loan, which it did last month. The rest of the U.S. investment is in the form of an equity stake that the government can start selling off after GM launches an IPO.

In addition to the U.S. stake, the United Auto Workers owns 18 percent through a trust for retiree health care, the Canadian government has 12 percent and GM's bondholders have 10 percent.

GM Chairman and CEO Edward E. Whitacre has resisted making public any timetable for GM's offering. He backed off an earlier target of 2010 set by his predecessor Frederick "Fritz" Henderson.

Whitacre has said the move to go public depends on market conditions and the company's financial position. Both the administration and GM say the automaker will make the call on when to go public.