The Nationals are being accused by Labor of "dirty tricks" in two crucial byelections in Murray and Cootamundra over messaging the ALP alleges is attempting to masquerade as official NSW Electoral Commission material.

Nationals volunteers, including a staff member in deputy premier John Barilaro's office, have been wearing fluorescent orange vests and handing voters a leaflet informing them: "You don't need to number every box".

A Nationals staffer at a polling booth in Young.

Labor alleges the tactic is aimed at tricking voters into believing they are distributing official NSW Electoral Commission material.

The Nationals' are running a "Just Vote 1" strategy in the byelections in a bid to reduce the number of preferences that might flow to the Shooters candidates who are their main threats in the seats.