Andy Burnham won the Makerfield by-election with 55% of the vote, defeating Reform UK and Restore Britain. His majority of 9,231 votes exceeded that of his predecessor, Josh Simons.
Burnham's victory came amid calls from senior Labour figures for a leadership contest. Harriet Harman urged Starmer, Burnham and others to test their parliamentary support without involving the wider membership.
The result marked Burnham's return to Westminster after nine years away, having previously served in the governments of Tony Blair and Gordon Brown. He described the outcome as a turning point for Labour and a chance to build a new politics based on unity.