One of Keir Starmer's Cabinet allies has failed to deny claims that Keir Starmer is poised to quit tomorrow amid feverish speculation about the Prime Minister's future.Peter Kyle, the Business Secretary, did not knock back reports that Sir Keir will announce as early as Monday that he is leaving Downing Street.The PM is said to have reached the conclusion that his position is no longer tenable after talking to Cabinet colleagues, No 10 advisers, union leaders and key Labour donors.Sources insisted Sir Keir, who is this weekend discussing his future with his wife Victoria at their country retreat Chequers, had yet to make a final decision. Mr Kyle confirmed that Sir Keir was reflecting 'on the political realities and challenges' in the wake of Andy Burnham's thumping win in the Makerfield by-election, which has sparked fresh calls from Labour MPs for Sir Keir to quit.The PM is now under huge pressure to set out a timetable for his departure and to make way for Mr Burnham in a possible coronation for the former Greater Manchester mayor.Asked about the reports the PM is planning to announce his resignation, Mr Kyle told Sky News: 'I have nothing to believe that they are true. I'm seeing a lot of speculation out there. 'The only thing I can say with fact is that the Prime Minister is hard at work, as he is every day - he is one of the most hard-working people I've ever come across.'Today, as in every other day I have ever known Keir, he is out there working hard.'At the same time he is also trying to create the space where he can think and reflect on the political realities and challenges and the opportunities that lie before us.'As Britain prepares for a seventh different PM since the Brexit referendum a decade ago:Mr Burnham is being warned against making Ed Miliband his Chancellor should he become PM – or risk his premiership being 'over before it's begun';Tory leader Kemi Badenoch has killed off any prospect of an electoral pact with Nigel Farage after Reform UK's poor showing in last week's by-elections in Makerfield and Aberdeen South;Mrs Badenoch cited Reform's support for 'a bigger state, more spending, nationalisation, gimmicks and unfunded giveaways', saying: 'Reform dress like Thatcherites but act like Corbynites';New polling shows more than half of Britons think Sir Keir should resign while Mr Burnham's popularity is plummeting even before he reaches No10; One of Keir Starmer's Cabinet allies has failed to deny claims that Keir Starmer is poised to quit tomorrow amid feverish speculation about the Prime Minister's future. Peter Kyle, the Business Secretary, did not knock back reports that Sir Keir will announce as early as Monday that he is leaving Downing Street Mr Kyle confirmed that Sir Keir was reflecting 'on the political realities and challenges' in the wake of Andy Burnham's thumping win in the Makerfield by-electionAsked if Sir Keir had now come to the conclusion it is in the interests of the country for him to resign, Mr Kyle said: 'All I know for fact is that he is engaging in conversations with a wide range of people, including myself.'He is, as well as working really hard over this weekend, I think he is making time to reflect on the political realities, challenges and opportunities that he finds himself in.'I think that is what people would expect him to be doing at this moment in time.'Downing Street on Saturday night responded to the reports that Sir Keir is poised to quit by insisting the position was unchanged from Friday, when the PM vowed to fight on and said that he would not walk away from a leadership challenge.Sir Keir said then: 'If there is a contest, yes, I will run. I have said repeatedly I am not going to walk away from that.'But, asked in a later TV interview if it was still true that Sir Keir would fight any challenge to his leadership, Mr Kyle would only say: 'Well he's fighting for our country.'And today he is hard at work as he has been every day that I have known him as leader of the Labour Party and PM.'He is also making time this weekend to try and reflect on the political challenges that he faces, our country faces, our party faces.'Pressed again on whether Sir Keir was still planning to fight a leadership challenge, Mr Kyle told the BBC: 'These are decisions for Keir to make.'That's why I said that he is taking the time - as well as dealing with all the issues that a PM deals with over a weekend, a very busy weekend - that he's also taking the time to think through what the political realities are today compared to last week, the week before.'But I know that he is a PM who always put the country first and he will be framing every decision he makes today on behalf of the country in his day-to-day job as PM, but also when he thinks about the party going forward, it will always be about what's in the best interests of the country.'Mr Kyle admitted there was 'clearly political uncertainty' when quizzed about whether Sir Keir is thinking about setting out a timetable for handing over power to Mr Burnham.He added that the Government would make sure that 'whatever unfolds' in the coming days will be a 'functional process' whereby the Labour Party puts the 'interests of the country first and foremost'.'Now, I can't predict the future,' he added. 'I don't know what's going to unfold in the days that lie ahead.'I don't know the decisions that he will make on behalf of our country as he considers these issues, and then makes decisions.'But we will find a way for this to be whatever unfolds, a functional process, one where the Labour Party is seen to put the interests of the country first and foremost, and we will carry on delivering for this country through whatever does unfold in the days ahead.'That's because Keir demands it.' Sources insisted Sir Keir, who is this weekend discussing his future with his wife Victoria at their country retreat Chequers, had yet to make a final decisionAs he spent Sunday at Chequers considering his premiership, Sir Keir took the time to post on social media about Father's Day.He wrote on X: 'Being a dad is my greatest joy. 'Today, I'm thinking about my dad, and the father I am to my children because of him. Happy Father's Day.'A Labour peer claimed the PM would not 'walk away' from Downing Street and create a political vacuum. Instead, he would 'arrange a slow march as a matter of duty and dignity'.Mr Burnham, who trounced Reform UK at last week's by-election in the Greater Manchester seat, will be sworn in as an MP tomorrow.Sir Keir is under pressure to make his intentions clear before Tuesday's Cabinet meeting. Another Labour grandee said: 'He's come up hard against the reality that the support isn't there.'The truth is everyone knows this is no longer a tenable proposition. There's a sadness about it all but sometimes there's just an inevitability in politics.'