Threats to Starmer's right-hand man could expose PM

History is littered with the resignation letters of those who have tried to drive a wedge between Keir -Starmer and Morgan McSweeney.

- Jessica Elgot

But that relationship is now facing its biggest test with the spotlight on the conduct of McSweeney as the former director of Labour Together and whether there was any ill intent behind late declarations of more than £700,000 in donations.

The relationship between the prime minister and his chief of staff has often been called a marriage of convenience - and that has some merit.

Starmer rewarded the man who delivered him a decisive leadership victory and then a historic election majority. McSweeney identified Starmer as the most plausible candidate to defeat Corbynism after the defeat of Jeremy Corbyn in 2019 - and crafted a platform.

But there is more to their partnership than expediency.

Starmer has tried out other chiefs of staff over the years but none have suited him like McSweeney.

His second chief of staff, Sam White, was a bad fit. His third, Sue Gray, tried to marginalise McSweeney and made enemies in the process, ultimately leading to her own exit.

Starmer has until recently implicitly trusted his strategic advice. There were whispers about McSweeney's position after Starmer seemed to question that strategy in government in an interview with his biographer, Tom Baldwin. Starmer then made a dramatic show of defending his chief of staff to the whole cabinet, saying unequivocally that he believed they all owed their positions to the soft-spoken Irishman.

But unhappiness with the party's rock-bottom poll ratings and a series of unforced errors means many of McSweeney's internal critics are now sensing their chance to force a change of direction.