ExxonMobil has warned that energy investment will shift out of the US if the government bans fracking, the drilling technique that transformed oil production but is opposed by three Democratic candidates for president. The oil supermajor has invested heavily in the Permian Basin of Texas and New Mexico, increasing volumes there by 72 percent year on year. The once-moribund basin was reinvigorated by horizontal drilling and hydraulic fracturing, or fracking, which frees hydrocarbons from tightly packed shale rock.

Democrats Kamala Harris, Bernie Sanders, and Elizabeth Warren have each called for a halt to fracking in response to environmental and climate concerns. Ms. Warren, a US senator from Massachusetts, tweeted in September that she would ban ¬£racking “everywhere” on her first day in the White House. Over the past decade, the US has more than doubled crude oil production to 12m barrels a day, largely due to fracking. Neither President Donald Trump nor his predecessor Barack Obama sought to prohibit the technology.

The prospect of a sharp break in policy has unnerved energy executives. A universal ban could drive oil prices to $85 a barrel – compared with $55 in the US today- according to Tudor, Pickering, Holt, an investment bank.

“I think any efforts to ban fracking or restrict supply will not remove the demand for the resource,” Neil Hansen, Exxon’s vice¬≠ president of investor relations, said on an earnings call on Friday. “If anything, it will shift the economic benefit away from the US to another country, and potentially impact the price of that commodity here and globally”.