Starmer reflecting on political reality as he considers future | Sunday with Laura Kuenssberg

Sir Keir Starmer is reflecting on the "political realities" he now faces, a cabinet ally of the prime minister has said, in a sign he is contemplating stepping down.

Business Secretary Peter Kyle told the BBC that any decision he makes "will always be about what's in the best interest of the country", while referencing the "chaos" of leadership challenges under the Tories.

Calls for the PM to set out an exit timetable have grown after Andy Burnham's decisive victory in the Makerfield by-election mean he can now challenge Sir Keir for the Labour leadership.

A growing number of figures in government believe the prime minister is preparing to set out plans for his departure as early as Monday.

In the immediate aftermath of Burnham's victory, Sir Keir continued to insist he would fight any formal leadership bid, in a process that would potentially take months to resolve.

But in a shift in tone, Kyle told the BBC's Sunday with Laura Kuenssberg that the prime minister was "taking the time to think through what the political realties are today, compared to last week and the week before".

He added that "every decision he makes today" about Labour's future would reflect "what's in the best interests of the country", Kyle said.

Asked whether this meant the prime minister was entertaining some form of orderly transition, the minister said: "The reality right now is that there is process under way, there are people who seek to challenge Keir."

But he added that he did not know what might happen in the coming few days, and stressed that the government intended to "govern through whatever unfolds or may not unfold in the days ahead".