Rudd declared climate change "the great moral challenge of our generation" and his government proposed an emissions trading scheme (ETS) to address the issue. The necessary legislation, however, was twice rejected in the Senate when the Opposition and Greens refused to support it. After the December 2009 UN Climate Change Conference in Copenhagen failed to produce an agreed international response to global warming the government decided to postpone its ETS until 2013, a decision which saw Labor lose some electoral support to the Greens. The government also lost some public support when it proposed a Resources Super Profits Tax following the release of the Henry Tax Review in May 2010. The resulting media campaign against the tax by the mining industry particularly affected Labor's support in the resource-rich states of Queensland and Western Australia.