Blackheath resident Dick Harris said such moves could be regarded as a waste of taxpayer money.

Mr Harris has been a Nationals member and branch executive for more than 40 years and said flaws were brought into focus by the preselection process under way to endorse a Nationals candidate to replace retiring Member for Calare John Cobb.

Among the candidates to be considered at the preselection vote this weekend is sitting Member for Orange Andrew Gee.

“Should Mr Gee be selected and then go on to win the federal seat this will necessitate a byelection for the state seat at considerable cost,” Mr Harris said.

He said this would cost taxpayers more than half a million dollars.

“As a member of the National Party for over 40 years I believe not only the Nationals but all political parties should change their rules so that no member who has been elected by the constituents to represent them can abandon the seat mid term,” Mr Harris said.

However, he said there could be mitigating circumstances including health reasons affecting the member or the member’s family.

Mr Harris urged Mr Gee and those eligible to vote at the weekend to take into account the cost of a possible byelection.

Mr Gee retained his seat at the 2015 state election with more than double the primary vote of his Labor opponent.

He is one of four candidates to face the selection panel at the weekend.