Which will help Greece more – voting "yes" or "no" to accepting more austerity demands from creditors?
Greek Prime Minister Alexis Tsipras says a "No" vote would strengthen his hand to negotiate a better deal.
But proponents of a "Yes" vote, including a parade of former prime ministers and the main opposition party, say backing his government will jeopardize Greeces place in the club of 19 nations who use the common euro currency. Instead, they argue by voting "Yes" Greece would get a new deal quickly to shore up its sinking economy.
Conservative opposition leader Antonis Samaras cast his ballot Sunday, saying "we vote 'yes' to Greece. We vote 'yes' to Europe."