Australia's parliament has rejected a plan for the world's most ambitious emissions trade regime, bringing the nation closer to a snap election and prolonging financial uncertainty for major emitters. Conservative lawmakers holding the largest block of votes in the Senate joined with Greens and independents to defeat the Carbon Pollution Reduction Scheme set to start in July 2011 and aimed at reducing emissions in the biggest per-capita emitter in the developed world. But the Government renewed its pledge to push through the scheme before a December UN meeting in Copenhagen, where world nations will try to hammer out a broad global climate pact and where Canberra is eager to take a leading role. "This bill may be going down today, but this is not the end," Climate Change Minister Penny Wong told the Senate. "We will bring this bill back before the end of the year because if we don't this nation goes to Copenhagen with no means to deliver our targets," Wong said before the vote. Greens wanted tougher emissions targets, while conservative opponents are divided on the need for a scheme and want it delayed until after Copenhagen, fearing Australia will be disadvantaged if other nations fail to act on climate change. Prime Minister Kevin Rudd has promised emissions cuts of 5-25 per cent on 2000 levels by 2020, with the higher end dependent on a global agreement to replace the UN's Kyoto Protocol. But if the Senate blocks or rejects the legislation a second time, after an interval of three months, it will hand Rudd a trigger for an early poll likely to be dominated by climate change.