Labor says the Abbott government is at war with itself as Liberal MPs sound each other out over the leadership.

Sources have told The Australian Financial Review that “footsoldiers” for both Malcolm Turnbull and Scott Morrison have been taking informal soundings in recent days targeting colleagues who backed Tony Abbott in the attempted leadership spill in February.

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“This is a government at war with itself,” shadow treasurer Chris Bowen told reporters in Canberra on Tuesday.

The soundings come as a Newspoll shows the safe Liberal seat of Canning is at risk in the by-election on September 19.

The first poll of Canning voters taken since the death of their Liberal MP Don Randall last month reveals the coalition’s hefty 11.8 per cent margin in the West Australian seat has almost evaporated.

On a two-party preferred basis the Liberal Party leads Labor 51-49 per cent, raising fears it could be the first seat a government has lost at a by-election since 2001.