Steven Rattner will depart as head of the U.S. autos task force that oversaw unprecedented bankruptcies at General Motors Corp and Chrysler Group, Treasury Secretary Timothy Geithner said on Monday.

Ron Bloom, a senior member of the White House/Treasury Department task force and a former Wall Street executive and labor restructuring expert, will take over day-to-day responsibilities for Rattner, who will soon return to private life in New York, officials said.

Rattner is a former journalist, investment banker and co-founder of private equity fund Quadrangle, which he left in February to join the Obama administration.

An administration official, who was not authorized to speak for attribution, added that Rattner's departure represents the start of a long-planned wind down of the autos panel, which was formed in February to restructure GM and Chrysler.

Geithner said the government's role would shift from restructuring the automakers to monitoring their businesses. He said taxpayers have a much better chance of recouping their investment in both companies now that restructuring has been completed.

With the emergence of both General Motors and Chrysler from bankruptcy, we enter a new phase of the government's unprecedented and temporary involvement in the automotive industry, Geithner said.

Last week, Rattner likened the post-bankruptcy operating strategy of the task force to that of an institutional investor that holds a large stake in a public company. It aims to look after the taxpayers' investment without meddling in operations, exercising voting power to approve board members, but not other company decisions.

The government owns 60 percent of GM with a $50 billion stake and 8 percent of Chrysler/Fiat with more than $12 billion in taxpayer bailout funds.

Rattner also said that he hopes GM will be in a position to launch an initial public stock offering in the first half of next year for at least a portion of the government's stake, returning the automaker to public stockholder ownership.

Both have received tens of billions of government aid in a restructuring that was capped by swift trips through bankruptcy to shed debt, brands, dealers and other assets. Chrysler formed an alliance with Italy's Fiat.

A Chrysler official had no immediate comment, while GM could not be reached for comment.

(Reporting by John Crawley, David Lawder and Nancy Waitz in Washington and Megan Davies in New York; editing by Carol Bishopric)

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