BELEAGUERED Prime Minister Sir Keir Starmer is vowing to fight to hold on to 10 Downing Street if challenged by Manchester Mayor Andy Burnham.

Should Mr Burnham return to the Commons after the Makerfield by-election next week he has made clear he will seek to replace Sir Keir as Labour leader.

There has been some hope that Sir Keir, having led Labour to a historic defeat across Britain in last month’s local elections, might agree to step aside.

However, Downing Street is making it clear that Sir Keir would not go quietly, and would make it clear that any minister who wished to back Mr Burnham would have to resign from the government.

This would plunge Labour into chaos, splitting the party as it embarks on a leadership election that could last more than two months.

Mr Burnham appears to be on course to prevail in Makerfield in the face of a strong challenge from Reform UK in a seat which Labour has held for more than 120 years.

His campaign is relying heavily on his personal appeal, with Labour branding absent from his posters.

Many Labour MPs believe that only Mr Burnham, the country’s most popular politician according to opinion surveys, can turn around the party’s cataclysmic polling figures.

Sir Keir, however, remains determined to tough out the crisis and holds to a hallucinatory belief that he can be premier for the next decade.

MPs told the Star that they believe that concerted Cabinet pressure might yet force him to stand down when Mr Burnham mounts his challenge, but warn that there might still be a contest involving the Blairite former health secretary Wes Streeting.