Either a new treaty of a major reworking of existing ones is needed to sort out the eurozone
He is facing calls from the Eurosceptics to demand repatriation of powers from the EU ( whatever that means) as a price for signing up to any alterations to the various EU treaties that all 27 EU members are signatories of.
It would be easier for the 17 Eurozone countries to use amend existing treaties to make the changes they need to ensure Euro stability rather than having a new deal just for the 17. However any change to existing treaties needs the approval of all 27. If Cameron blocks change he will be very harshly thought of by other EU leaders and will lose further influence
If Cameron plays tough on this it will result in the UK being frozen further from the centre of the EU with even less influence and will anger the Lib Dems, if he doesn't play hardball he will anger the eurosceptics in the tory party who want a referendum and argue that any new deal triggers a referendum under the laws Cameron passed.
Can he keep everyone on side? Placate the two extremes of the coalition and not bee seen as a spoiler in Germany and France?
He is in big trouble here - could be his biggest test. He is in hock to Europhiles and Eurosceptics and I see no way out for him
Is he a good enough politician to wriggel out of this? Its his biggest test to date.

