British Prime Minister Keir Starmer was weighing the “political realities” facing his government, a senior minister said Sunday, amid media reports that he could resign within days.

This follows veteran Labour politician and rival Andy Burnham's victory in a by-election Friday, which paves the way for the 56-year-old to challenge Starmer for party leader and prime minister.

Any Labour leadership candidate must be a member of Parliament.

If Starmer leaves office this year, Britain will get its seventh prime minister in a decade – an unprecedented rate of churn in its modern history.

Burnham, Greater Manchester mayor since 2017, made clear his intention to bid to lead the center-left party, warning in his by-election victory speech that it had a "final chance to change." If successful, he would become prime minister, given the ruling Labour Party's large parliamentary majority.