Greece's referendum polls are on a knife edge - and a close result could be the worst outcome

ATHENS, Greece - the pivotal referendum that will decide this country's future is just two days away, and it's impossible to call.

If Greeks vote "Yes" to the snap vote called by Prime Minister Alexis Tsipras just a week ago, they'll be accepting a bailout deal which may not even be on offer from its European creditors any more.

If they vote "No," they'll reject that shaky agreement, potentially forgoing support for their shattered banking system, and beginning a chain of events which could force the small country out of the euro.

Two polls Friday morning are pointing in different directions - on shows a narrow Yes victory, the other a narrow win for No.

The first, commissioned by Bloomberg and conducted by the University of Macedonia, has 43% in favour of Yes and 42.5% in favour of No.

But a much bigger gap has closed since the referendum was announced - apparently when the poll started, before banks closed, 52% backed No and just 26.5% backed Yes. That's not the first poll that has showed this effect.

The second poll, commissioned by Ethnos (a newspaper) and the ALCO pollster shows a similarly close result, but with Yes narrowly in the lead. Yes has 44.8% of those surveyed, while No has 43.4%.

Both polls are so close that it's impossible to give either side a definitive lead - but it looks like No has been losing support since banks were shuttered.

Almost all polling suggests that the vast majority of Greeks are keen to keep the euro as the national currency. As a result, politicians opposed to the government want to portray Sunday's vote as a referendum on the euro for obvious reasons.

No (Oxi) posters have popped up everywhere in Athens, and apparently further afield in places like Thessaloniki too. There are fewer visible adverts for Yes (Nai), but it's clear there's a groundswell of support for accepting the bailout deal.

One thing which could be particularly bad is if there's an extremely close vote - there's a lot of paranoia among the activists on both sides at the moment, and if either lost by less than say, 5%, it would be very easy for them to construct reasons for which the vote was unfair - that is was manipulated by the media or the government.

A narrow no vote, particularly, would be an extremely thin mandate to leave the eurozone on, and could turn the social unrest we've seen so far into something far uglier.