In Australia’s Westminster system, governments depend on MPs for support – and MPs can be replaced part-way through the term or change their minds about who to support.

Since Federation, the governing party changed eight times due to non-electoral events, most recently in 1975 with the Dismissal of the Whitlam Government.

While in 1975 it was the Governor-General who forced a change, the other seven were caused by MPs changing their minds about who to support or governments failing to get their agenda passed through the parliament.

A government can also lose its parliamentary majority outside of a general election but hold on to power.

In 2018, when Malcolm Turnbull quit Parliament and independent Kerryn Phelps won his seat, the Morrison Government fell into minority. The government survived, although legislation to allow for medical evacuation of sick refugees and asylum seekers became law despite the government’s opposition.

At the state level, since 1992 there have been three times when crossbenchers have forced a change in premiers or ministers, without bringing down the rest of the government – most recently in Tasmania last year.

Crossbenchers can demand the old convention of ministerial responsibility is upheld without threatening the survival of the government as a whole.