WASHINGTON (Reuters) - The U.S. Treasury Department said on Friday it will sell $4.5 billion worth of American International Group stock, taking another step toward unwinding its position in the financial crisis bailout programs.

The sale could cut the government's stake in the insurer to just above 50 percent. The move accompanies President Barack Obama's campaign for a second term in which he has been forced to defend his administration's decision to use taxpayer money to prop up companies during the crisis.

The insurer, which received multiple bailouts under both the Obama and Bush administrations, intends to buy up to $3 billion of the offering once it is priced, Treasury said in a statement.

Brokers at Morgan Stanley Smith Barney are receiving allocations of AIG's shares at a price of $30.50 a share, a source familiar with the allocations said on Friday.

Assuming Treasury conducts the offering at this price, the sale would represent about 147.5 million shares of AIG stock. That would suggest the offering would reduce Treasury's stake in AIG to about 52 percent from the current 61 percent holding.

The insurer, which is still not overseen by a single regulator, is expected to be slapped with a "systemically important" label from the powerful new U.S. council of regulators. The label would then subject AIG to new rules as well as supervision from the Federal Reserve.

The U.S. government hired Citigroup Inc, Deutsche Bank Securities, Goldman Sachs, JPMorgan Securities, Morgan Stanley and Credit Suisse to coordinate the offering.

AIG closed at $31.34, above the $28.72 price the government needs to break even on its investment in the insurer.

(Reporting By Ben Berkowitz, Lauren Tara LaCapra, Rachelle Younglai; Editing by Andrew Hay, Bernard Orr)