There may be a thaw in Afghanistan's disputed presidential election crisis.

A U.S. official says Afghan President Hamid Karzai is expected to concede Tuesday that he's short of the 50 percent vote he needs to avoid a runoff with his nearest rival.

What's not clear yet is whether there will actually be a runoff or a power sharing deal between Karzai and former Foreign Minister Abdullah Abdullah.

The U.S. government official discussed the matter on condition of anonymity because Karzai had not yet announced his decision.

The U.S. preference is for a power-sharing deal to avoid the expense and risk of a second election.

A U.N.-backed fraud investigation threw out nearly a third of Karzai's ballots, but an Afghan-led Independent Election Commission has yet to accept and certify the results.