It came hot on the heels of his centre-left Labour party finishing a humiliating third in a crunch by-election Thursday in a former heartland seat, ratcheting up the pressure on Starmer.
The latest ministerial departure also follows the embattled UK leader defying calls within his own party to resign earlier this month, in the wake of numerous policy U-turns and missteps.
That included appointing Peter Mandelson, who had longstanding links to the late US sex offender Jeffrey Epstein, as Britain’s ambassador in Washington.
Starmer fired him months into the role after new details about the extent of Mandelson’s friendship with Epstein emerged, creating a firestorm in the UK that threatened to topple the Labour leader.
In the latest controversy, Labour MP Josh Simons said he had resigned as a minister in the Cabinet Office, which helps deliver the government’s agenda, because he had “become a distraction” from that work.
The lawmaker had faced weeks of calls to quit over claims a Labour-supporting think tank he headed from 2022 to 2024 had paid a PR firm to investigate the background of at least two prominent journalists.
In a letter to Starmer, Simons insisted he had been unaware of those probes “until a few weeks ago” and said the prime minister’s ethics czar had cleared him of breaching ministerial rules.
In his reply, Starmer said he had accepted his resignation “with sadness”.
It is the latest exit from his government, which has trailed in the polls to Nigel Farage’s hard-right Reform UK for over a year and appears increasingly threatened by the rise of the left-wing Green Party.
The Greens won Thursday’s by-election for a Manchester parliamentary seat, beating out Reform and forcing Labour, which easily won the seat in 2024, into third place.
Starmer earlier this month saw his influential ex-chief of staff Morgan McSweeney resign in the wake of the Mandelson scandal, while Labour figurehead Angela Rayner quit as deputy prime minister last year following a separate controversy.
The UK leader faces fresh peril when voters in swathes of Britain head to the polls for local elections on May 7.