Bank of America Corp., Citigroup Inc., Goldman Sachs Group Inc., JPMorgan Chase & Co. and other big banks are marshaling opposition on Capitol Hill to kill a proposal by House Ways and Means Committee Chairman Dave Camp (R-Mich.) to tax the nation's largest financial firms, the Wall Street Journal reported today. The companies are curtailing financing for GOP lawmakers and warning of an economic hit. A summary of Camp's legislation said that he proposed the tax on large financial institutions in part because it would offset the lower borrowing costs they receive from a perceived government backstop. The big firms dispute that such a subsidy exists. The tax, tucked into a broader tax-revision package announced last month, is aimed at bringing in $86 billion in revenue over the next decade and eliminating what his staff calls a "massive taxpayer-funded subsidy" big banks receive from the perception the U.S. would step in to prevent their collapse.