Geithner warned that would have "painful implications" for everyone from members of the armed forces to Social Security recipients and small business owners.
Geithner said the idea of a "debt ceiling budget" to let the government keep operating for some indefinite period was "unworkable."
Treasury already has 40 cents of every dollar spent so such a proposal could leave it in a position where it had to cut about 40 percent of all government payments, he said.
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