A fellow blogger has written an article in which he contends that the happiest hunting ground for the opposition should be the towns and villages in the north of Moldova. This is because (a) they voted heavily for the communists on 5 April, but (b) they have low levels of ethnic minority voters (the communists' most loyal support base). The theory is that if the opposition can spread the truth about what happened in April, and (tacitly) about Russia's support of Voronin, then these voters could be persuaded to switch allegiance, at least to the PD if not to the liberal parties.
The converse also holds. There is little point in putting effort into Chisinau or its suburbs (already a liberal bastion) or into places like Balti and Gagauzia which are dominated by Russian-speakers.
It would be nice if there were not a correlation between ethnicity and voting patterns - as I have written before I believe Russian speakers have as much to gain from a true democracy as ethnic Moldovans do - however in the current campaign we need to be pragmatic, recognise that differences do exist and adjust strategies accordingly.