One must not vote for individuals based only on shallow reasons like a favourabe impression.
First and foremost, one must base one's choice only on what moral principles that person subscribes to. This is of paramount importance, for human moral is of paramount importance for any society. If a good person joins a party which has proven itself to be rogue, then voting for that person is a grave error of judgement. Also, if the person is motivated largely by personal material gain and glory rather than a concern for fellow human beings, voting for that person is bound to worsen the moral rot or decay already present.
On the other hand, good persons who are in the opposition here evidently have strong moral character simply by virtue of the fact that they are making a tremendous personal sacrifice in the face of adverse circumstances and against a 'big and bad' adversary. Such real sacrifice is impossible for those whose sole motivation is material gain. As for voting, I for one will definitely vote humanely in the interest of humanity at large.