After a year of clashing with Washington over new financial reforms, the country’s most powerful bankers have found common ground with regulators in the hard-fought effort to lift the debt ceiling and avoid a default.

Wall Street is no longer watching from the sidelines as the most polarizing political fight in years plays out on Capitol Hill. In the last few days, top executives have been in close contact with Washington in a last-ditch attempt to prod lawmakers toward a compromise by Tuesday, the administration’s deadline to reach a deal.

On Friday, Jamie Dimon, JPMorgan Chase’s chief executive, raised concerns with Treasury Secretary Timothy F. Geithner about the standoff over the debt ceiling and its potential to disrupt the system through which JP Morgan and other big banks disburse federal payments. Mr. Geithner assured him that the Treasury and Federal Reserve had taken steps to keep the payment system functioning smoothly, according to individuals briefed on the call.

In addition, more than a dozen chief executives from the nation’s biggest financial services firms wrote a joint letter to President Obama and members of Congress on Thursday warning of “very grave” consequences for the economy and the job market if an agreement wasn’t reached.