So letting the public decide their own fate is now called "shifting blame"?
Apparently this didn't work out (ultimatum by the EU), but how could they find out without at least trying to negotiate with the EU.
He wasn't voted into power to leave the Eurozone, he was voted into power to end austerity and stay in the Eurozone.
When should he have called for a referendum? After the first negative response they received from the EU? This would be silly.
Of course they tried to negotiate and to explore all possibilities until they either reached a mutually acceptable agreement with the EU or they received a final ultimatum.