President Barack Obama unveiled plans on Thursday to limit the size and scope of United States banks and financial firms in a new offensive against Wall Street excesses laid bare by the financial crisis. "Never again will the American taxpayer be held hostage by a bank that is too big to fail," vowed Obama, flanked by former Federal Reserve chief Paul Volcker, who advised the president on the rules. The plans aim to limit "excessive" risk-taking and to "protect" taxpayers by preventing banks or financial institutions from owning, investing in or sponsoring hedge funds or private equity funds. They will effectively force financial firms to choose between proprietary activities -- trading in stocks and sometimes risky financial instruments for their own benefit -- and traditional activities, like making loans and collecting deposits. The initiative, which must be approved by Congress, includes a new proposal to limit the consolidation of the finance sector, placing broader limits on "excessive growth of the market share of liabilities" at the largest financial firms. Obama blamed banks for sparking the worst economic crisis since the Great Depression with "huge reckless risks in pursuit of quick profits and massive bonuses" in a "binge of irresponsibility". "My resolve to reform the system is only strengthened when I see a return to old practices at some of the very firms fighting reform; and when I see record profits at some of the very firms claiming that they cannot lend more to small business, cannot keep credit card rates low, and cannot refund taxpayers for the bailout," the president said. He vowed to enact the reforms in Congress, even if Wall Street deployed an army of lobbyists to kill them. "If these folks want a fight, it's a fight I'm ready to have," he vowed defiantly.