Australia's election campaign will officially start soon with climate change policy and union corruption in the national building industry shaping into key battlegrounds for the July 2 poll. Prime Minister Malcolm Turnbull said Wednesday that he was likely to visit Governor-General Peter Cosgrove this weekend to lock down the date and officially start the election campaign. A heartening historical fact for Turnbull is that no Australian federal government has lost power after a single three-year term since the tumultuous early years of the Great Depression. But Australia is now in an extraordinary era of political volatility as it grapples to diversify an economy that thrived on a mining boom that has gone bust. If the opposition center-left Labor Party wins the election, it will mean Australia's fifth change of prime minister in six years.