The Privacy Act, but then there is a legal void in relation to the political parties. The Privacy Act applies to all federal institutions, but the information held by political parties is not covered by the Privacy Act.
Let's therefore put your scenario in the situations where personal information would be discussed or shared in, let's say, a confidential debate. It would never be shared in a public debate unless the information is no longer protected, because, for example, it is already in the public domain. If it is exchanged in a confidential debate, it must be protected to that level of sensitivity that personal information requires. Should there be, let's say, an accidental disclosure, it would be the Privacy Act that would govern the consequences, so the obligations applicable would most likely be the Privacy Act.