NSW byelections to be first big test for Dominic Perrottet and Chris Minns. Here’s what to look for

After almost 11 years of Coalition dominance in New South Wales, could Labor be about to mount its comeback?

Saturday's byelections in four New South Wales state electorates are likely to have wide-ranging impacts.

The worst case scenario for the premier, Dominic Perrottet, would see the state government lose its stable majority in the lower house of parliament. More likely, though, is that these byelections could set the tone for next year's state election.

The Coalition is set to become the longest-serving conservative government in modern NSW history in March, when it exceeds the 11 years it spent in power from 1965 until 1976.

Only one government in the last half century has lasted more than 12 years - the last Labor government, which served from 1995-2011.

Winning a fourth election is historically difficult, and Saturday's byelections will provide valuable insights into whether the Coalition is beginning to be weighed down by history.

All four byelections were triggered by the resignations of senior members of the parliament: