CANBERRA, Australia (AP) — Australia's prime minister used his official campaign launch on Sunday to warn against a change of government during the economic fallout from Britain's decision to leave the European Union. Australia's only two surviving conservative prime ministers — John Howard and Tony Abbott — had front row seats at the campaign launch. An opinion poll published in Sydney's The Sunday Telegraph newspaper found the government and the center-left Labor Party opposition running neck and neck with each supported by 50 percent of respondents.