WASHINGTON — President Barack Obama today called for a new tax on Wall Street's largest firms to cover a projected $117 billion shortfall in the government's financial crisis bailout fund.

In remarks prepared for a White House appearance, Obama said he was determined that every dollar spent from the $700 billion Troubled Asset Relief Program to rescue Wall Street firms, auto companies and mortgage holders is either repaid or paid for in some fashion. Congress would have to approve the tax.

"My determination to achieve this goal is only heightened when I see reports of massive profits and obscene bonuses at the very firms who owe their continued existence to the American people who have not been made whole, and who continue to face real hardship in this recession," Obama said in his prepared remarks.

The president is proposing a levy of 0.15 percent on the liabilities of large financial institutions. The tax, which officials are calling a "financial crisis responsibility fee," would apply only to financial companies with assets of more than $50 billion.

Those firms — estimated to amount to about 50 institutions — would have to pay the fee even though many did not accept any taxpayer assistance and most others already paid back the government.

The administration expects that 60 percent of the revenue would come from the 10 largest firms. The fee would go into effect June 30 and last at least 10 years.