Eurozone finance ministers have postponed their decision on a 12bn-euro ($17bn; £10bn) loan to Greece until it introduces further austerity measures.
The ministers said they expected to pay the latest tranche of a much larger aid package by mid-July.
But its release depends on the Greek government surviving a vote of confidence on Tuesday.
Parliament then must also pass 28bn euros worth of new spending cuts and economic reforms.
This latest tranche - of a 110bn-euro European Union and International Monetary Fund aid package - is crucial as Greece needs the aid by July to pay off the creditors of its huge debts.
But there are also practical questions about whether the country can implement the reforms being demanded in return.
Greeks have already seen wages and pensions cut and there have been regular, mass demonstrations - even riots - in protest.
BBC