Lower voting age "gimmick": government

The federal government has dismissed Labor's plans to lower the voting age to 16 as a gimmick.

"I don't believe there will be much public support (for it)," cabinet minister Mathias Cormann told Sky News on Saturday.

Opposition Leader Bill Shorten will make the case for 16 year olds to get the vote in a speech in Sydney, telling the NSW Young Labor conference young people deserve a say in Australia's democracy.