US President Donald Trump framed his sweeping rollback of federal climate change policy on Thursday as a political win over the Democratic Party's 'radical' environmental agenda, reprising a message Republicans have used in past elections and could turn to once again ahead of November's crucial midterms. His announcement at the White House was one of the most significant moves of his second term in office. The president said he was revoking an Obama-era 'endangerment finding' from 2009 which held that pollution harms public health and the environment. For almost 17 years, the US has used that scientific finding as the legal basis to establish policies to reduce emissions from cars, power plants and other sources of planet-warming gases. 'This radical rule became the legal foundation for the Green New Scam,' Trump said, using a term popular with Republicans for describing Democratic environmental and climate policies. The move marks the culmination of a decade-long push by Trump to tear up policies that Democrats and many climate experts say are needed to rein in emissions. And it is one of the most far-reaching reversals of American climate policy yet. Trump, who has called climate change a 'hoax' and a 'con job', dismissed the science underpinning the Obama-era rule in remarks that at times took on the air of a victory lap over his Democratic opponents. He focused on the economic impacts of reversing the endangerment finding, arguing that boosting fossil fuels instead of clean energy would lead to lower energy costs for American consumers, adding that the US auto industry would be a major beneficiary of the change. The rollback sparked fury among Democrats and environmental groups who said it would wreck the US's ability to combat climate change. Critics argue this decision will lead to a decline in environmental protections, making it harder to fight against climate change and its impacts. In recent years, climate policy in the US has swung wildly depending on who is occupying the White House, but this announcement represents the largest move yet by Trump to dismantle previous climate policies. The implications of this shift will likely be a focal point as the Republican Party tries to gain support in the upcoming elections.