It's generally assumed that Treasury would make sure that the government wouldn't default on Treasury notes held by investors, including foreign countries like China, If it did default on such debt obligations it could be a catastrophe for the economy.
A House-passed stopgap spending measure pending before the Senate contains a GOP-backed provision that would give Social Security recipients and bondholders priority in receiving payments from the government.
Lew again rejected the idea.
"The United States should never have to choose, for example, whether to pay Social Security to seniors, pay benefits to our veterans, or make payments to state and local jurisdictions and health care providers under Medicare and Medicaid," Mr. Lew said. "There is no way of knowing the damage any prioritization plan would have on our economy and financial markets. It would represent an irresponsible retreat from a core American value: We are a nation that honors all of its commitments."
Lew again warned that President Barack Obama would not negotiate with Republicans over the debt limit.
"The president remains willing to negotiate over the future direction of fiscal policy, but he will not negotiate over whether the United States will pay its bills for past commitments," Lew wrote. Extending borrowing authority does not increase government spending; it simply allows the Treasury to pay for expenditures Congress has already approved."
Republicans want to add budget cuts and other legislation like a one-year delay of "Obamacare." House leaders hope to bring a debt limit increase to the floor by the end of this week but they haven't released any details yet.