Just hours after Louise Haigh resigned as transport minister after admitting that she had a minor criminal offence relating to a mobile phone she wrongly said had been stolen, Starmer appointed Heidi Alexander, who served as the deputy mayor for transport in London between 2018 and 2021.
It was a swift replacement to try to draw a line under the resignation, yet another blow to the Labour leader who has seen his party's approval ratings plunge since it won a July election over a raft of tax rises that have targeted businesses, farmers and pensioners.
Haigh said in a letter to Starmer that she had told police she had lost a mobile phone during a "terrifying" mugging on a night out in 2013, only to discover later that the phone was still at her home.
In her resignation letter shared by Starmer's office early on Friday, Haigh said she was standing down as the issue "will inevitably be a distraction from delivering on the work of this government and the policies to which we are committed".
The opposition Conservative Party said Haigh had "done the right thing" but asked why Starmer had appointed her when she said he was aware of her fraud conviction.
"The onus is now on Keir Starmer to explain this obvious failure of judgment to the British public," a spokesperson for the Conservative Party said in a statement.
Almost immediately after winning power, the Labour government came under fire for limiting fuel payments to the elderly and for taking donations for clothing and hospitality.
Since then, his government has angered farmers over changes to inheritance tax rules and many businesses have complained about Labour's first budget when the government announced the biggest tax increases in a generation, mainly on companies and the wealthy.
Haigh, who was first elected in 2015 and has held senior posts under both Starmer and progressive former Labour leader Jeremy Corbyn, said the incident with the phone was a "genuine mistake" from which she "did not make any gain".
She had been the youngest member of the cabinet aged 37 and was responsible for government policies including the rail nationalisation bill, which became law this week.
