Hello Emma and thank you for your really interesting question.
The Australian Constitution – the set of rules by which Australia is governed – gives 3 separate groups: the Parliament, the Executive, and the Judiciary, the power to make and manage Australian laws. This is known as the separation of powers and ensures that no one group is more powerful than another.
Looking specifically at the Parliament, which consists of the Queen (represented by the Governor-General), the Senate and the House of Representatives, there are 4 key people who have significant responsibilities or powers. These are:
The President of the Senate and the Speaker of the House of Representatives. Together they are the presiding officers of the Australian Parliament. They are the most powerful members in meetings of the Senate and the House of Representatives because other members can only speak with their permission.
The Prime Minister who is the leader of the government and, amongst other things, has the power to select members to be ministers and advise the Governor-General about constitutional matters.
The Governor-General who has the power to appoint and dismiss ministers and provide Royal Assent to bills – proposed laws – passed by the 2 houses of Parliament.
At different times and settings, 1 of these 4 may have more influence than the others, but it is not really possible to say who is the most powerful person in Parliament.