WASHINGTON — Senate leaders are closing in on a path for dealing with the “fiscal cliff” facing the country in January, opting to try to use a postelection session of Congress to reach agreement on a comprehensive deficit reduction deal rather than a short-term solution.

Senate Democrats and Republicans remain far apart on the details, and House Republicans continue to resist any discussion of tax increases. But lawmakers and aides say that a bipartisan group of senators is coalescing around an ambitious three-step process to avert a series of automatic tax increases and deep spending cuts.

First, senators would come to an agreement on a deficit reduction target — likely to be around $4 trillion over 10 years — to be reached through revenue raised by an overhaul of the tax code, savings from changes to social programs like Medicare and Social Security, and cuts to federal programs. Once the framework is approved, lawmakers would vote on expedited instructions to relevant Congressional committees to draft the details over six months to a year.

If those efforts failed, another plan would take effect, probably a close derivative of the proposal by President Obama’s fiscal commission led by Erskine B. Bowles, the Clinton White House chief of staff, and former Senator Alan K. Simpson of Wyoming, a Republican. Those recommendations included changes to Social Security, broad cuts in federal programs and actions that would lower tax rates over all but eliminate or pare enough deductions and credits to yield as much as $2 trillion in additional revenue.