The ferocious backlash against the £5bn in welfare cuts crafted to balance the books in this Wednesday’s spring statement highlighted an increasingly glaring conflict, between Labour’s pre-election tax pledges and the party’s wider purpose.

Since Rachel Reeves promised last autumn to deliver a single, annual budget, she has been confronted with rising debt interest costs, weaker-than-expected economic growth, and the near-collapse of the transatlantic alliance. “The world has changed,” as every Treasury press release now has it.

When she delivers her spring statement this week the chancellor will eschew tax rises and instead squeeze future spending plans, to ensure the forecasts show her fiscal targets being met, five years from now.

This package will include the welfare cuts already announced, but the Treasury is also expected to seek another £5bn in savings elsewhere.

The political logic is impeccable, and well-rehearsed. Labour made sweeping tax pledges in the run-up to last year’s general election, so is adamant that it cannot touch broad-based taxes, such as income tax.

Reeves already rewrote the fiscal rules significantly at her autumn budget, allowing for more borrowing to fund capital investment, and she whacked up taxes by £40bn, the biggest package of increases since 1993.

And there is an economic logic too, born of genuine fear in the Treasury that bond markets could take fright – causing a Liz Truss-style crisis – if Reeves tears up the framework she set herself just six months ago. Hence the pressing urgency of identifying £5bn of welfare cuts. Hence, lest we forget, the slashing of the UK’s already denuded aid budget, to pay for increased defence spending.

It all looks perfectly sensible within the framework Labour has set for itself. And the bond market worry can’t be easily dismissed: the UK is already spending £100bn a year on debt interest.

Nevertheless, viewed from a wider angle, the idea of responding to this profoundly uncertain moment for the world with nip-and-tuck spending cuts, looks at best like a holding position, and at worst like a pointlessly destructive act.

And while bond market jitters may be a legitimate reason to be wary of plunging deeper into the red – for example by “doing a Germany” and excluding defence spending from debt rules – opting for spending cuts, rather than tax rises, is a political choice.

Economists, including many previously supportive of Reeves’s approach, have lined up in recent days to issue warnings against wielding the scalpel too hastily.

Gemma Tetlock, of the Institute for Government, advised the chancellor against “reaching for little bits and pieces to try and get the numbers to just about add up”.

The former Bank of England chief economist Andy Haldane used an article in the FT article to warn against allowing ”Treasury orthodoxy” to dominate Reeves’s thinking.

“With the economy stalled, further fiscal belt-tightening is impossible to justify on macroeconomic grounds,” he wrote.

And while the forecasts are by their nature highly uncertain, the impact of the welfare cuts and the wider spending squeeze will be concrete, as impact assessments set to be published alongside the spring statement will show.

With the pressure for higher defence spending in the UK only likely to increase, the row about benefit reform, which followed Annaliese Dodds’ resignation over aid cuts, is likely to be a mere foretaste of the clashes ahead.

And each of these tussles is likely to leave some Labour supporters, if not the target voters party strategists dream about, wondering what their party is for.

As if to remind Labour of the challenges it cannot confront within existing fiscal constraints, the day after the chancellor is on her feet official data on poverty in the UK will be published.

The annual official Households Below Average Income (HBAI) release, for 2023-24, will give a snapshot of how many families in the UK were struggling to get by, as the party came to power last year. Campaigners say this will be a key baseline, against which to track Labour’s progress in improving the lives of the poorest in society. In particular, the data is expected to show that the number of children in larger families living in poverty has increased, as more are caught in the net of the pernicious two-child limit.

Charities are also expecting to see evidence that Scotland’s anti-child poverty policy, which includes an additional Scottish Child Payment of £26.70 a week to low-income households, is having a positive effect.

As Save the Children’s executive director for advocacy, Dan Paskins told me, “it will show the scale of the challenge, but also show what are the things that a government that is genuinely serious about tackling child poverty can do to reduce it – and we can then draw conclusions about whether government does that, or doesn’t”.

The long-awaited child poverty strategy is now expected in June. But such is the caution about cost that Paskins says experts who work on this issue are now genuinely asking themselves, “Is this going to be the first ever Labour government under which child poverty is higher at the end of its term in office than at the start?”

Of course, if Labour decides that something has to give, there are alternative revenue-raisers within the constraints of those pre-election promises, but they either involve an array of small yet hotly controversial changes (see farmers’ inheritance) or big and untried levies that would take time to implement.

Breaching the tax pledges would be risky, even with Trump’s disruptive power to point to as an explanation. But clinging to them even as the world has changed risks leaving Labour cast adrift from its principles.