New Delhi, June 21 -- Labour's Andy Burnham, the popular mayor of Greater Manchester, won a special election for a seat in Parliament and signaled Friday that he will use it to challenge embattled Prime Minister Keir Starmer for leadership of the country.

Starmer said he planned to fight for his job, but a growing number of colleagues urged him to make a dignified exit.

"There is this sense of collective movement," former Labour Deputy Leader Harriet Harman told the "Electoral Dysfunction" podcast. "Andy Burnham is going to become prime minister. Keir Starmer is going to be leaving office."

Burnham decisively won the seat of Makerfield in northwestern England over Rob Kenyon of the anti-immigration party Reform UK. The result cements t...