As the presidential campaign gets under way in earnest, the policies unveiled on 4 September by the USA’s governing Democrat party attempts to draw a distinction between oil production and the “cheap, abundant natural gas” that they are putting forward as the best candidate to help bring jobs and industry back to the United States.

At the same time, the Democratic platform is toning down its assessment of the severity of global warming and what the United States should be doing to arrest it — a major turnaround from four years ago, when the party warned that “the epochal, man-made threat to the planet” of climate change had to be halted. In time this formed the background to environmental pledges made by the party’s candidate and incoming president Barack Obama.

These changes of attitude reflect recent changes in the availability of fossil fuel, and the cost to the country of maintaining low carbon initiatives. The recent surge in domestic production of natural gas from shale gas is bringing jobs to Ohio, Pennsylvania and other tightly contested states.

At the same time, the economy nationwide has undertaken broad initiatives to combat global warming — including cap-and-trade programmes that would put a price on carbon dioxide emissions, a difficult line to sell in an ailing economy.

In fact both the Republicans and the Democrats have linked economic gains to domestic gas production. “Our dependence on foreign oil is now at a 16-year low, and a new era of cheap, abundant natural gas is helping to bring jobs and industry back to the United States,” the Democrats say in their platform. “We can move towards a sustainable energy-independent future if we harness all of America’s great natural resources.”

The Democratic Party says that means “an all-of-the-above approach to developing America’s many energy resources, including wind, solar, biofuels, geothermal, hydropower, nuclear, oil, clean coal and natural gas.” Apparently it also includes boosting energy efficiency and supporting investments in infrastructure needed to speed up the transition to natural gas-powered vehicles and other cleaner transportation fuels. there is not however much enthusiasm for oil expressed in the Democrat policies.

Republicans, by contrast, focus heavily on the production side; their party platform, released last week, emphasises ways the United States can harness the nation’s “incredible bounty” of oil and natural gas – for instance, by expanding oil and gas development offshore and on the coastal plain of the Arctic National Wildlife Refuge. But there is no mention of natural gas as a transportation fuel. Republican lawmakers are wary of committing to the federal investments necessary to boosting the development of filling stations and other infrastructure.

Although the two parties differ widely on climate change, both have altered their approach compared to four years ago. The Democrats’ dire warnings have given way to a more pragmatic approach, emphasising the need for an international framework for tackling the issue, as well as “efforts to combat climate change at home” but stop short of endorsing a specific domestic approach, such as a cap-and-trade plan or carbon tax. Republicans’ only mention of climate change is to decry the Obama administration’s national security strategy for elevating it to a “severe threat equivalent to foreign aggression.” But four years ago, Republicans advocated “measured and reasonable steps” to reduce the human impact on the environment and “address the risk of climate change based on sound science.” including “market-based solutions” to curb emissions.