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

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

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