Ukraine's election map, year after year, is even more reliably split between red/blue - west/east, than the USA's electoral map.
If the goal is a land-corridor to Crimea, that is the 'blue' area for sure, but how much Russian-speaker support can Russia count on?
I believe there was polling that showed that a super majority of Ukrainians, even in the East, oppose what is happening. It is not as “split” as you believe, or as the Russian propagandists want us to believe.