Why did Syriza choose to forge an alliance with the right-wing, racist ANEL?  There were alternatives.  One was to coalesce with a neoliberal, austerian centrist bloc.  Another was to form a minority government, although from the responses by Syriza members and supporters, this doesn't even seem to have come up.  What is more, since negotiations lasted less than an hour, and given Syriza's previous history of working with ANEL, there are good prima facie grounds for assuming that the deal was done some time ago.  And indeed, reports I've seen suggest sections of Syriza were hoping for ANEL to get enough votes to justify such a coalition.

This is, at least in part, the result of a strategic decision by the leadership of Syriza.  And we need to understand this in order to avoid reductionist explanations of the following type: 

i) it's a tactical expediency, caused by the need to get a parliamentary majority to face down the troika.  There is a tactical element, but that tactic already presupposes a strategy based on negotiations and foregrounding national sovereignty.

ii) it's the dirty politics of government, inevitable when you enter the capitalist state and try to administer a rotten system.  But this was not a necessary compromise forced by the structure of the bourgeois state or the electoral system.  It is an informed gamble.  Putting it down to the pitfalls of administering capitalism, which are real, is just a manifestation of Beautiful Soul leftism.

iii) it's the fault of the left-of-Syriza groups, particularly KKE, who have played a rotten sectarian game and left Syriza with few options.  The sectarianism of the KKE continues to merit criticism, and a change of attitude on their part could still make a difference to the dynamics.  But give Tsipras et al the dignity of having their own strategy: they wanted this outcome, and they'll want bragging rights if it succeeds.

iv) it's original theoretical-strategic sin, as reformists will always place national unity and class compromise ahead of working class struggle.  This is the answer of the broken clock left.  If it were as simple as this, To Potami would fit the purpose just as well.  Or New Democracy.  Or Pasok.

The point is this.  Syriza is playing a long game. They do want to transform the Greek state, Greek civil society, and of course the EU in a socialist direction.  To this end, they seek to coordinate the mobilisation of the popular classes, most centrally in the form of social movements, with a parliamentary strategy of building alliances and 'resistances' in the state.  

The reason they don't simply look to win elections and rely on governmental power to solve all problems is because their own political traditions tell them that the state is a terrain of struggle on which the dominant classes enjoy the overwhelming advantage.  Winning executive power is almost useless if it is quickly isolated, encircled, and the locus of dominant state power shifted to another apparatus like the judiciary.  So, traversing the state means forming alliances with subaltern forces in the state - not just parliamentary parties, but public sector workers, sympathetic civil servants, lawyers unions, reasonable police chiefs who might help constrain, reform or break up authoritarian power networks, and so on.  It means using such power as can be gained to modify social relations in the interests of the popular classes, strengthen the social movements and unions, while reciprocally leaning on those movements to bolster their own position inside the state.  

The leftist variant of this strategy foregrounds another element, which is what Poulantzas called 'ruptures': sudden offensives both inside and outside the state which enable dominant class power networks to be broken up, state power to be recomposed, wealth and power to be sharply transferred to/taken by workers.  This is an antidote to the gradualism of certain 'Gramscian' approaches which are predicated on the idea of developing socialist hegemony in the form of a 'national consensus' before the working class takes political power.

However, the immediate objective is to break the grip of the memorandum and debt servitude on Greek society.  Syriza did propose an anti-austerity government of the Left to address this.  What is more, at that time their slogan was 'not one sacrifice for the euro' - a slogan pushed by the organisations' left-wing, not at all favoured by its 'realists'.  This created the prospect of a popular, left, working class-led government, and it was resonant enough with the mood of Greek workers that Syriza overtook Pasok as the main party of the working class left.  They were rebuffed by parties to their left for mainly sectarian reasons and, at any rate, lost the election.  This, combined with the subsequent decline in popular mobilisation, strengthened Syriza's 'realists'.  And they had an alternative strategic concept, more cautious than that of the 'government of the left': a 'national' government comprising anti-memorandum forces which could break the rule of the troika, restore democracy and reverse key planks of austerity.

As far as I can tell, the Syriza leadership and parliamentary bloc first dabbled with an alliance with ANEL during the Cypriot banking crisis in 2012-13.  In his response to the crisis, Tsipras argued that the European leadership was colonising the south, using debt servitude as its main instrument.  This clearly articulated one dimension of the Greek struggle, which is the struggle for national self-determination.  Greece's position in the European imperialist chain, the attitude of the troika to Greek public opinion, the effective cancellation of democracy, are all as central as the struggle against the Greek bourgeoisie.  And indeed, Syriza distinguishes between different fractions of the bourgoisie - the oligarchs tied to what Pablo Iglesias called the 'Finance International', and the 'national' or 'subaltern' bourgeoisie who want capitalism to be made to work again, but for whom the memorandum doesn't work.  So this strategic idea of, to give it the 1970s Gramscian gloss, a 'national-popular', cross-class alliance to break the memorandum, has a very definite referent in the nature of the Greek struggle and in Syriza's analysis of Greek capitalism.

ANEL makes a certain sense as a partner in this.  It is right-wing in ways that only a UKIP Facebook forum on chemtrails would fully understand and its leader, Panos Kammenos, is a thug.  However, it represents the breakaway from the main capitalist party, New Democracy, on the specific axis of the memorandum.  And it is in a way ideal for the Syriza leadership because it is anti-memorandum without being anti-euro.  Moreover, it also has a 'popular' character: if this election followed past form, its support will have been concentrated in the working class, and weak in the middle class - to this extent, its electoral profile more closely resembles that of a leftist party than New Democracy.  So, for almost two years now, Tsipras et al have been maintaning contacts with ANEL on the basis of their shared opposition to the memorandum.

Looking at this coalition, there is a natural concern with what will happen to Syriza's commitments on immigration, civil liberties and social rights.  These are indeed central, and there is a lot that can go wrong here.  But it's important to recognise the concessions that have already been made.  Pursuing an alliance with a right-wing populist party to present the EU with a firmly anti-memorandum government necessitated significantly moderating the programme.  This is exactly what happened.  The gap between the 2012 '40 point plan', and the 2014 'Thessaloniki programme' is not negligible.  And the most significant retreat is dropping the nationalisation of the banks.  

Nevertheless, on the 'national' front there is a sense in which this alliance is not moderate.  Syriza, having accepted that breaking the memorandum would be a matter of diplomacy and negotiations, decided that they would need a strong majority government with a clear and intransigent anti-memorandum mandate. The alliance with ANEL has given them exactly this.  There is no point in prevaricating about this: it has plainly rattled the EU, and in a strictly short-term, realpolitik sense, in terms of negotiating with the EU in the coming months, it is not a stupid move.

This alliance is thus not the result of original theoretical sin, nor a purely tactical gambit, nor something that is forced on Syriza. It is a convergence of a strategic perspective associated with right-Eurocommunism, tactical calculations deriving from the dynamics of parliamentary majorities and negotiations, and contingent elements of the terrain such as the flux of popular struggle, and the attitude of other leftists.  It is an informed calculation which can precisely be criticised as such.