On Saturday, NSW voters will go to the polls in four byelections in what will be the first electoral test of pandemic politics since sentiment began to turn against those in charge.

While the NSW Liberal government should hold at least two of the three seats it is defending, and possibly all three, it will be the size and nature of the swings that will be watched closely, both at a state level and federally. NSW Premier Dominic Perrottet is the canary in the coal mine.