PM denies he's gone soft on republic

Prime Minister Malcolm Turnbull has dismissed suggestions his passion for climate change action, a republic and gay marriage has gone missing.

"I'm not going to run a commentary on myself," Mr Turnbull told 5AA Radio in Adelaide when quizzed about where the "old Malcolm" had gone.

But he confirmed he would be voting `yes' in a flagged plebiscite on legalising same-sex marriage if the coalition won the July 2 election.