Labor has rejected suggestions that the federal electoral laws should be changed to allow optional preferential voting.
Some senior Liberals reportedly want to change the laws so that voters would not have to number the ballot and give preferences to candidates they may not support.
Currently, voters have to put a number next to every candidate to lodge a valid vote.
Some Liberals believe changing this will hurt the Greens and Labor, The Australian has reported.
Opposition electoral affairs spokeswoman Bronwyn Bishop told The Australian that optional preferential voting should be considered because it would lessen the informal vote.
"By having optional preferential voting, people feel far more confident that they are not being forced to allocate a preference to somebody they do not want," she said.
The informal vote rose 1.6 per cent nationally at the 2010 election.
However, Special Minister of State Gary Gray told AAP the current system was consistent and reliable.
"The system shouldn't be changed to the advantage of one political party or another," he said.
"Elements of the system are older than the parties.
"It should not be tampered with for partisan advantage."
Mr Gray said while it was "absolutely appropriate" to have the debate, it was not appropriate to change the mechanics of a system that still worked well.
"Any change to the system should address the problems in the system," he said.
Last week, the Gillard government attacked the Queensland LNP government of Campbell Newman after it released a discussion paper unveiling a raft of possible voting reforms, including querying whether voting should be a choice.
LNP senator Barnaby Joyce has also spoken out against changing the system.
Mrs Bishop said the discrepancy between some states where voters can choose to vote preferentially and the federal preferential system had led to a "great rise" of informal voting in federal elections.
"(Putting) a one or just allocating one preference is valid at state level for Queensland and NSW, but invalid federally," she told ABC radio.
"So to have an optional preferential vote means that you would increase the valid votes that are cast."
Acting Opposition Leader Warren Truss dismissed suggestions the coalition was moving to change the present system.
The Nationals oppose optional preferential voting because of its impact on three-way contests where the party fields a candidate against its coalition partner, the Liberals, and Labor.
"There will always be healthy debate about these issues," Mr Truss told Fairfax Media.
"But the coalition has no plans or policy to change the current system of compulsory preferential voting."