So for the survival of a party survival of its cause is imperative and there has to be identity of purpose between it and its members. Power alone cannot be the purpose of a party though it may be a means to an end. Purposelessness is bound to result in defections from the party. In certain circumstances it may attract defectors from other parties but as soon as the circumstances, power in particular, disappear, these bandwagon riders will leave the party in search of new pastures. It is futile to expect that parties themselves will shun such defectors or, at least, will not allot positions of advantage and prestige to them.
Opportunism is a two way affair.
It is unfair to blame only the defectors. Parties that avail of the support of defectors are as much guilty. And then the main culprit is the purposelessness of both, the parties and their members. Had they any purpose, defection would not be even thought of. The first gives a handful of legislators with shifting loyalties, dominating control over the affairs of this vast and sprawling country, without making them answerable to anybody for their actions except their conscience if they have any.