FAMILY First Senator Bob Day is set to lodge a legal challenge against the Federal Government's new Senate voting laws in the High Court this week.
The Coalition-sponsored bill, which will make it harder for minor parties to get elected, passed both houses on Friday after a marathon sitting.
Under the new legislation, voters who give a limited number of preferences will have their ballot discarded if their preferred candidates are excluded from the race.
Prime Minister Malcolm Turnbull said the passage of the legislation was good for democracy because Australian voters would determine where their preferences go rather than backroom deals.
Senator Day said he would argue the new laws could potentially disenfranchise voters and three million votes could exhaust or die as a result.
Liberal Democrats Senator David Leyonhjelm is also supporting the High Court challenge.
Senator Day expected other crossbenchers to join the action