Greece's European partners have said this could see the country slide from the 19-nation eurozone, with unforeseeable consequences for Athens and for Europe's grand project to bind its nations into an unbreakable union by means of a common currency.
The uncertainty over Greece's future sparked long queues at ATMs in the country, where anxious citizens could only withdraw 60 euros ($66) per day.
"I feel like I'm voting for sudden death or slow death," said 38-year-old office manager Maria in Athens, who wants Greece to stay in the EU. "It feels like it's game over."
The deadlock has led to declines on global stock markets, with US and European stocks suffering heavy losses. And banks in Athens remain shut in order to avert financial collapse.
Felt betrayed
In Brussels, European Commission President Jean-Claude Juncker said he had felt betrayed by Tsipras' left-wing government and called on Greek voters to oppose him."I'd like to ask the Greek people to vote 'Yes.' ... I very much like the Greeks, and I'd say to them, 'You should not commit suicide because you are afraid of death,'" he said in an emotional speech.
"A 'No' would mean, regardless of the question posed, that Greece had said no to Europe," said Juncker, previously Tsipras's closest ally in five months of debt talks.
Other EU leaders including Germany's Angela Merkel, France's Francois Hollande, and Italy's Matteo Renzi put up a united front, stressing that the bailout referendum was effectively a vote on Greece's place in the euro.
EU leaders have indicated they are still open to an agreement to avoid a Greek exit, which would leave a permanent scar on the 28-member bloc.
Also, the Greek Prime Minister said that he won't cling on to his job, if he lost this Sunday's referendum on whether the country should accept the terms of a bailout.
