Senior Liberals have warned the NSW government faces a “humiliating loss” in the Wagga Wagga byelection because of an “expensive but lacklustre campaign” that missed the mark.

The scathing assessment from the premier’s MPs comes as it emerged that the Liberals’ candidate Julia Ham only joined the party three months ago.

Ms Ham became a member of the Liberals’ Tumbarumba branch in June and needed special dispensation from the party to contest the Wagga preselection because party rules stipulate six months’ membership.

Liberal candidate Julia Ham hands out how to vote cards on Thursday Credit:Nick Moir

The Liberals are facing a bitter battle in Wagga Wagga and senior government Liberals have slammed the campaign, arguing the leadership has been “tone deaf”.