Carper, chairman of the Senate Homeland Security and Governmental Affairs Committee, and Issa, chairman of the House Oversight and Government Reform Committee, were aiming to complete a bill during the lame-duck session but couldn't narrow their differences in time.
"While our approaches have differed in the past, we made significant progress in narrowing our differences in recent months, and our commitment to restoring this American institution to long-term solvency is unwavering," Carper and Issa said.
Postmaster General Patrick Donahoe said the agency's financial problems could be reversed swiftly through legislation.
Donahoe said the agency has already changed part of its five-year comprehensive business plan, including the pace of consolidation of mail-processing facilities.
"The Postal Service has worked closely with the Congress over the past two years to advance a framework for a viable business model that will allow us to quickly respond to the evolving needs of our customers," he said.
In an effort to reduce costs, the postal service has cut 60,000 employees in the past two years, consolidated 70 mail processing facilities and reduced hours at many post offices, while increasing package volume and introducing a same-day delivery service.
"We encourage the new 113th Congress to make postal reform an urgent priority, and to work steadily toward the quick passage of reform legislation," Donahoe said. "We will continue to work with leaders of our House and Senate oversight committees and all members of Congress to help make this happen.”
The Senate passed its bill back in April, but the House didn't bring the bill approved by Issa's committee to the floor.