WASHINGTON -- Democratic leaders on Capitol Hill are drawing up plans to toughen oversight of the financial industry and considering introducing another economic-stimulus package in the wake of the government's decision to buy stakes in major U.S. banks.

House Speaker Nancy Pelosi is mulling recommendations from several economists that Congress act on an economic-recovery package that would cost taxpayers $300 billion, according to congressional aides, equivalent to about 2% of the country's gross domestic product.

The...