Morgan Stanley and JPMorgan are the top candidates for the lead underwriting roles in the General Motors initial public offering, The Wall Street Journal reported, citing people familiar with the matter.

JPMorgan was not immediately available to comment. Morgan Stanley and GM spokesman Tom Wilkinson declined to comment. The U.S. Treasury, which owns nearly 61 percent of the automaker's common shares, was also not immediately available for comment.

The Treasury, which provided $50 billion in bankruptcy and bailout financing to GM, hired Lazard Ltd last month as an adviser on the IPO. Lazard is being paid $500,000 per month until an IPO is completed under its 18-month contract with the Treasury.

Timing on the offering is uncertain, but the Obama administration on Thursday said it would not happen before the fourth quarter.