WASHINGTON (AP) -- With defaults on credit card debt spiraling amid a global financial downturn, banks already reeling from the mortgage crisis are losing billions more from unpaid credit card bills.

Big banks have formed an unusual alliance with consumer advocates to urge the government to allow huge portions of credit card debt to be forgiven, a turnabout from recent years when the banking industry lobbied strenuously to make it harder for consumers to erase their credit card debts in bankruptcy.

The new pilot program -- which the banks hope will become permanent -- could involve as many as 50,000 people struggling with credit card debt. On an individual basis, the amount of debt to be forgiven would rise according to the severity of the borrower's financial situation, up to a maximum of 40 percent.

Amid rising job losses, consumers -- even those with strong credit records -- have been defaulting at high levels on their credit cards. Banks already battered by the mortgage and credit crises are bleeding tens of billions in red ink from the losses. The largest credit-card banks each set aside between $1 billion and $3.5 billion in the third quarter for losses on card loans as their profits plummeted.

Credit card charge-off rates, balances written off as unpaid, rose to 6.8 percent in August, up 48 percent from a year earlier, according to Moody's Investors Service.

Americans are lumbering under about $900 billion in credit card debt, according to the latest available Federal Reserve figures. People who are in credit counseling, on average, carry seven cards.