He served in an Obama administration that oversaw a historic surge in American oil and gas production, as shale went mainstream. Tens of thousands of wells were drilled and energy-bearing rocks fractured from North Dakota to Texas. And the industry cheered when the government he was part of lifted a ban on crude exports in 2015.

Yet, Joe Biden — armed with a commanding lead in the polls ahead of November’s US presidential election — now promises a root-and-branch overhaul of the American energy system that will put climate change at its heart and which one worried industry adviser describes as “a Tet offensive” on the fossil fuels industry.

The plan, which will be aired again at the Democratic party convention this week, earmarks $2tn in spending over the next four years to use climate policy to drag the economy out of its pandemic-era recession. But Mr Biden’s plans for the energy sector would reach into everything from Middle East geopolitics to the global race with China over clean tech and is likely to prove unpopular among parts of the US electorate — dependent on oil and gas for jobs — in an election year.