The plan brokered by Mr. Buchheit, which required many private holders of Greek debt to accept big losses as part of the refinancing, was a last-minute resolution.

For now, Greece is living hand-to-mouth. It has been dipping into the reserves of various state bodies to pay monthly pension and wage bills. A senior official in the Finance Ministry said that there was about €2 billion of cash left to tap in this regard and that the government should be able to finance itself through Friday.

When Mr. Varoufakis flew on short notice to Washington on Easter Sunday to ask Ms. Lagarde for some payment flexibility, he said publicly that Greece intended to meet its obligations. The statement at the time was taken as a commitment by Greece to do whatever it took to pay the I.M.F. and others.

Privately, however, Mr. Varoufakis told colleagues in Washington last week that he purposefully used the word “intend” as opposed to “will” in his public statements on Greece’s payment plans, according to people close to the finance minister who spoke on the condition of anonymity.

Mr. Varoufakis is also well aware that if Greece continues to meet its payment schedule as currently mapped out, the country will end up paying about 12 percent of its gross domestic product to its creditors during his first term as finance minister.

He has said that such a dynamic is not sustainable for a left-wing government elected on a platform of putting the interest of Greece’s electorate before its creditors. The country was just emerging from a deep recession before the January elections and is thought to be slumping back into one.

European creditors and the I.M.F., meanwhile, have made it clear that they will not accept a delay in payment or a simple forgiveness of part of the debt — the sort of “haircut” that Mr. Buchheit persuaded private holders of Greek debt to accept in 2012.