UPDATE 1-Australia's government set to lose majority in landslide by-election defeat

Australia's centre-right government is poised to lose its one-seat majority in parliament after early counting in a crucial by-election on Saturday showed voters deserting the Scott Morrison-led government.

The governing Liberals suffered a 23 per cent swing against the party with just over 20 per cent of votes counted in the by-election for the constituency of Wentworth, according to the electoral commission.

The Australian Broadcasting Corp forecast the early swing was enough to strip the seat from the government, with an independent candidate emerging as the likely winner.

Should the projection hold, Morrison will be left relying on the support of independent lawmakers to continue to govern. The next election is not due until May 2019, although it could occur earlier if the government can't win the support of the independents.

Two independents have already ruled out supporting the government, and others have warned Morrison that he will have to pay a hefty price for their backing.