It seems to be economic policy orientation toward Europe or Russia, and not either language or ethnicity. Here is a new paper by Timothy Frye:
Language, ethnicity, and policy orientation toward Europe are key cleavages in Ukrainian politics, but there is much debate about their relative importance. To isolate the impact of candidate ethnicity, candidate native language, and candidate policy orientation on a hypothetical vote choice, I conducted a survey experiment of 1000 residents of Ukraine in June 2014 that manipulated three features of a fictional candidate running for parliament: 1) ethnicity as revealed by either a Russian or Ukrainian name 2) native language of Russian or Ukrainian and 3) support for closer economic ties with Russia or with Europe. The results reveal little difference in the average response to these 8 fictitious candidates despite the candidate’s different ethnicities, native language, and economic policy orientations. This seeming homogeneity masks vast differences in the responses of self-reported native speakers of Russian and Ukrainian. Analyzing the responses among Ukrainian and among Russian speakers yields considerable differences in the responses to the different candidates. Perhaps most striking is that among both native speakers of Russian and native speakers of Ukrainian a candidate’s economic policy orientation toward Europe or Russia appears to be a more important determinant of vote choice than a candidate’s language or ethnicity. That policy retains its importance for voters despite the intense politicization of both ethnicity and language and ongoing violence in eastern Ukraine suggests that vote choice in Ukraine has not been reduced to an ethnic or linguistic census.
Hat tip goes to www.bookforum.com.