Kevin Rudd has quit politics, bringing the curtain down on a volatile period for Labor and precipitating a by-election in his Brisbane seat of Griffith, proving an early test for both Tony Abbott and Bill Shorten .

The by-election, likely to be held early next year, is now poised to double as a referendum on Mr Abbott’s plans to axe the carbon tax and Labor’s plans to oppose it. It will most likely coincide with fresh Senate elections in Western Australia.