Queensland's electoral commissioner has insisted optional preferential voting will eventually improve the state's informal voting rates during a budget estimates interrogation.
Walter van der Merwe was called upon by the state opposition to explain how the new system, controversially introduced by the minority Labor government in April, will impact the level of informality.
Last week's Toowomba by-election, the first test of the procedure, recorded an informal voting rate of about 3 per cent - well under Mr van der Merwe's "reasonably generous" 8 per cent target.
"I can attribute that success to the media campaign I ran and the training of my electoral staff," he said.
"A success against your 8 per cent target, not a success against history," shadow attorney-general Ian Walker replied, referring to levels around 2 per cent in the past three state elections.
The Liberal National Party have been seething since April at the electoral changes which are expected to favour Labor and the minor parties at the LNP's expense.
Labor wrong-footed the opposition at the time by tacking on the optional preferential voting reform as an amendment to the LNP's legislation to increase the number of state MPs from 89 to 93.
Mr Walker challenged Mr van der Merwe on what evidence he had to back up his prediction of an improvement to the informal voting rate.
"With due respect, that's a policy decision," he replied.
The commissioner also revealed he was not consulted prior to the historic changes.
But Attorney-General Yvette D'Ath said the LNP presumably did not consult on its own changes either.
"If the LNP aren't happy about that, then quite honestly the only ones they should be looking at for answers are themselves," she said.
Informal Voting Rates in Queensland Elections:
- 2015: 2.11 per cent
- 2012: 2.15 per cent
- 2009: 1.94 per cent
Informal Voting Rates in Federal Elections:
- 2013: 5.13 per cent
- 2010: 5.45 per cent
- 2007: 3.56 per cent
Source: Qld Electoral Commissioner Walter van der Merwe