Sir Keir Starmer vowed to fight on as Prime Minister after spending the weekend weighing up his future.

He insisted he still intends to contest the next general election and will not walk away or set out a timetable for his departure if Andy Burnham returns to Parliament.

Sir Keir also said he would be '100 per cent' behind whoever is chosen to stand in the looming Makerfield by-election despite expectations his rival will challenge him for the Labour leadership if he wins.

His comments came after reports that the PM spent the weekend at his Chequers retreat considering whether or not he should find a way to step down from No 10 with dignity rather than risk being pushed out by the Greater Manchester mayor.

Asked directly on Monday if his premiership was over, Sir Keir replied: 'No, we've got a lot of work to do.'

He told how he visited Labour party headquarters earlier that day and reminded staff 'that we were elected into office by millions of people to bring about change in this country'.

Asked if it was still his plan to fight the next general election and serve a full second term in Downing Street, Sir Keir said: 'I do want to fight the next election.'

He admitted he needed to 'turn things around' after Labour's dire local election results, and hit out at the civil war that has engulfed his party since then.

'The last 10 days, there's been a lot of activity which hasn't been as focused in my view as it should have been.'

Asked if he would stand in a leadership contest if another MP finds the 81 supporters needed to trigger a challenge, the PM said: 'Well, we're not at that position, but I've said I don't know how many times that I'm not going to walk away.'

He admitted 'a lot of people in the Labour Party have been talking about what has to happen next' but said he was in politics to 'serve my country', in what may be seen as a swipe at his rivals' ambition.

And asked if he would set out a timetable to stand down if Mr Burnham wins the Makerfield by election, Sir Keir said: 'I'm not going to do that.'

He conceded it would be a 'very important by-election' that would be a 'fight between Labour and Reform'.

'I will be backing 100 per cent whoever the candidate is – not quite chosen yet, but soon to be chosen – whoever the Labour candidate is. I'll be 100 per cent behind them,' Sir Keir insisted.

He called on the whole of the Labour party to unite to win the contest.

'Whatever views people may have on the direction of the party, that needs to be put to one side.'

Earlier his Deputy Prime Minister warned Labour plotters they risk paving the way for a Reform election victory.

David Lammy told the BBC: 'Introspection and internecine warfare – effectively, some of our colleagues lighting the match and standing in the petrol – that is not what's going to deliver for the British people. What that will usher in is Farage.'

Speaking at an investment summit in Leeds, Mr Burnham said next month's by-election is 'very necessary'.

'I'm clear about what I am offering. If I get to stand, a vote for me will be a vote to change Labour, because Labour needs to change if we are to regain people's trust,' he said.