British Prime Minister Keir Starmer faced a major setback as the Green Party won a by-election in Gorton and Denton, a seat long held by Labour.

Green candidate Hannah Spencer secured 40.7% of the vote, marking the party’s first-ever by-election victory, while Labour fell to third place with 25.4%.

The result adds to Starmer’s challenges, following controversies like Peter Mandelson’s ambassadorial appointment and staff departures from Downing Street.

Analysts say the outcome signals growing voter openness to alternatives beyond Labour and the Conservatives, with Reform UK also performing strongly, CNBC has reported.

Starmer called the result “very disappointing” but acknowledged voter frustration and impatience for change.