If the euro fails, euro member-states may have to return to their old currencies.

FORBES: Who In the Private Sector Will Bailout Greece?

"If the euro fails, Europe doesn't fail, " he added, challenging an assertion made frequently by Mrs Merkel.

BBC: German anti-euro party holds founding conference

If the euro fails, then the danger is that many other things will disintegrate as well, like the internal market and free borders.

FORBES: Thoughts On Europe and the Nobel Peace Prize

Greece may be expelled from the euro zone if it fails to reach the agreement on forming the coalition government by the end of the day Sunday, Nov. 6, a Greek Skai radio station said citing official sources.

FORBES: Greece's Days In Euro May Be Numbered

In contrast, members of Angela Merkel's ruling party have talked of Greece leaving the euro temporarily if it fails to meet strict austerity conditions.

ECONOMIST: Charlemagne

If a closer union fails, some European leaders argue, the euro could unravel with dire consequences.

WSJ: As Ireland Flails, Europe Lurches Across the Rubicon

One of the worst scenarios is that Greece could fall out of the Euro in a messy, unplanned way for example, if it fails to secure aid and is forced to pay its civil servants in a different currency.

FORBES: What To Expect From The Eurozone In 2013

If the vote fails to get through Parliament, Cyprus faces potential bankruptcy and a possible from the euro, which could reignite concerns in financial markets over the future of the single currency.

NPR: Cyprus Seeks To Alleviate Pain From Deposit Raid