Prime Minister Scott Morrison and Opposition Leader Bill Shorten faced off in Perth last night for their first debate before the election next month.

The debate was strong but followed the usual headlines of the election to date, with Morrison pressing Shorten for the cost of his policies while Shorten attacked Morrison for favouring high-income earners and entering a preference deal with Clive Palmer.

25 of the 48 undecided voters who made up the audience gave the debate to Shorten, with 12 choosing Morrison and 11 remaining undecided.