Labor has launched a full-frontal attack on Prime Minister Scott Morrison, claiming a preference deal between the Coalition and Clive Palmer would deliver the most "extreme right-wing" government in Australian history.

Campaigning in Tasmania, Opposition Leader Bill Shorten accused Mr Morrison of being a "sneaky operator" who was willing to tell voters in Melbourne and Sydney one thing about a preference deal but another to voters through northern Queensland.

The Coalition is poised to do a preference deal with Mr Palmer's United Australia Party despite the businessman's controversial history, including the collapse of his Queensland Nickel refinery in Townsville which left hundreds of employees out of work and owed millions in entitlements.

Mr Shorten said a deal with Mr Palmer, along with a decision by The Nationals to preference One Nation ahead of Labor in some Queensland electorates, showed the "true colours" of the Coalition.