Wall Street is re-emerging as a force in Washington as it closesin on one of its biggest wins against regulation since thefinancial crisis.

With must-pass spending legislation making its way through Congress this week,banks seized on an opportunity to attach a measure that would halta planned restriction on derivatives trading they had longopposed. The industry's lobbying extended to the highest levels offinance, with JPMorgan Chase & Co. CEO Jamie Dimon pressinglawmakers to support the change.

Wall Street's success, after four years of struggling topersuade Congress to ease the Dodd-Frank Act, is a precursor tomore fights next year against some of the law's hallmarks: theconsumer protection bureau and stiff oversight of big financialcompanies whose failure could threaten the financial system.