The pro-Russian Opposition Bloc
Oh common, Opposition Bloc is not real, and everybody in Ukraine knows that.
It's a puppet, government-controlled party which does nothing but empty talk. In the real life they're supporting junta in comprehensive manner.
Just for example, Obozrevatel daily and Inter TV channel, which are owned by this so-called "Opposition Bloc", are full of ridiculous propaganda. In terms of following the state narrative, these "opposition" media are even more crazy than Poroshenko's own TV channel. That's why turnout is extremely low, people know that there is simply nothing to choose.