The UK still has a system that allows power to be abused, Keir Starmer has said, pledging after weeks of stories about lobbying, cronyism and cash for Boris Johnson’s flat renovations that the Labour party will “clean up our politics”. In the final days before polls close for local, mayoral, Welsh and Scottish elections, the Labour leader will attempt to draw a close connection between the stories of Tory sleaze and their effect on ordinary people. Labour sources said Starmer would link the row over Johnson’s lavish refurbishments to the early days of the pandemic and question whether the prime minister was distracted as he apparently sought donors to sponsor the decorations, which he has now funded himself. The Electoral Commission last week launched an investigation into whether any donations or loans to pay for the lavish refurbishment of his Downing Street flat were properly declared. Starmer will draw a clear distinction between his character and that of Johnson, describing his experience as a lawyer prosecuting MPs for false expenses claims. Labour will also try to forge a link between the cronyism of the distribution of Covid contracts and taxpayers’ cash, which advisers believe is key to making the damaging allegations stick. On Monday, Johnson again dismissed stories that he had sought donors to pay for his personal life – including a nanny – as “trivia” and said the election would be about bigger issues affecting people’s lives. In his open letter, Starmer writes: “I get angry when I hear how the friend and neighbour of a Tory minister gets £30m of taxpayers’ money, while towns and communities across the country see their local services cut. Or when I see the British people’s money wasted on government contracts that don’t deliver. “If I were prime minister, I would stop the abuse of taxpayers’ money, stop the wasteful approach to outsourcing contracts and clean up our politics. When I was director of public prosecutions, I was not afraid to prosecute MPs who had broken the rules over MPs’ expenses. As prime minister, I would not be afraid to overhaul a system that still allows power to be abused.” He said the choice would be between a Labour party that focuses on the country, or “a Conservative government busy providing favours for those who have ministers in their WhatsApp contacts”. The prime minister came under further pressure at the weekend over the donations row after the Scottish Tory leader, Douglas Ross, said Johnson should “of course” quit if he was found to have breached the code. Speaking to reporters on Monday, Starmer said it was significant that Johnson’s own party agreed it was unacceptable. “It’s very good to see senior Conservatives recognising the seriousness of the situation that the prime minister could be in and the implications of breaching ministerial code,” he said during a visit to Lewisham, south-east London. “Over the last week or so, some people have said holding the government, holding the prime minister, to account, is somehow party politics. This demonstrates that it isn’t – there’s a shared, cross-party need to uphold standards in public office, and I think other senior Conservatives should follow suit now.” On Monday Johnson was campaigning in Hartlepool, where the Tories are challenging Labour in a crucial byelection. Asked about refurbishments to his Downing Street flat, he said: “All this kind of stuff is absolutely not relevant to this campaign. And what I think the people of this country want to know is, who has the policies, who is actually talking about the issues that matter to the people of this country. “I know that people want to focus on trivia, but I’m focusing on the issues that matter.” Recent polls have shown a small shift towards Labour as the scandal has dominated front pages. Two of the most recent polls put Labour within five points of the Conservatives, with a Redfield Wilton poll on Monday showing just a two-point gap, having shown a 10-point gap last week. Starmer said he would “take full responsibility whatever the outcome” before the elections on Thursday. “I will take full responsibility for everything that the Labour party does,” he told reporters.