The distracting quasi-presidential race to become the UK’s next prime minister will, finally, come to an end on Monday. For the winning candidate, the highs of victory will rapidly give way to the reality of the task ahead. The new leader will inherit a fragile economy. Britain is projected to enter a lengthy recession as the energy crisis bites, with real household incomes set for their biggest fall in generations. Inflation is in double digits and forecast to go higher. Meanwhile the country is still struggling to overturn structural weaknesses that have underpinned its lacklustre growth since the 2008 financial crisis.

If the polls are to be believed, the frontrunner, Liz Truss, will beat the former chancellor, Rishi Sunak, and will be handed control of the economy. Truss’s campaign has offered little assurance that she will resolutely help households and businesses weather the current economic storm, let alone navigate longer-term challenges. Her low-tax, small-state agenda has appealed to the Conservative party members who choose the new leader. As prime minister, her priorities will change and she will need to revise her approach.

Her cabinet’s first priority will be to cushion the impact of soaring energy costs. Households face an 80 per cent rise in bills from October, while many businesses anticipate at least a fourfold hike. Truss has wavered on providing “handouts”, but has considered cutting VAT and suspending green levies. The latter would only tinker at the edges, and both would be poorly targeted. A failure to directly support at least the most vulnerable households and enterprises would be catastrophic for the economy, not to mention her 2024 electoral chances. She will need to spend billions, particularly if gas prices stay high.

While more borrowing will be necessary to handle the immediate crisis, Truss’s additional £30bn in promises to reverse increases in National Insurance and the planned corporation tax rise risk undermining the public finances. Public debt stands at about 96 per cent of UK GDP, the highest since the early 1960s. And unlike in the aftermath of both the financial crisis and pandemic — when some called for more borrowing to spur growth — interest rates are now rising too, making debt harder to service. Any fiscal headroom is likely to have shrunk. This means long-term debt dynamics could become unsustainable.

Stretching the public purse will be even harder with other urgent matters. Inflation is further denting health and social care budgets. Meanwhile, support on bills must come with efforts to improve efficiency and accelerate the shift to renewables and nuclear power. The long-term agenda also cannot be ignored. Boosting productivity — and levelling up the economy as promised — will need commitments on skills and infrastructure, not just tax cuts.

Something will have to give. It will be difficult for Truss to reconsider her tax pledges given how central they have been to the campaign. While she has already ruled out levying new taxes, she could at least stagger her corporation tax plan. Significantly pushing up borrowing could also be an option, albeit an irresponsible one, and likely to necessitate higher interest rates. Neglecting the NHS further would cost more lives. Overlooking productivity will mean Truss’s admirable ambitions for a high-growth, and ultimately lower tax, economy will remain a pipe dream.

Truss will need to switch from campaigning to governing. That is not a seamless transition in the best of times, let alone during an economic crisis. It will be even harder if Truss stays firmly tethered to her ideologies. Governing requires difficult choices. The more those choices are ignored, the harder they will become.