Keir Starmer has warned that the arrival of a new Conservative prime minister on Tuesday is not a “new dawn”, as he made a fresh pitch to voters to back Labour.

The Labour leader wrote in the Sunday Telegraph that he backed “common-sense, practical solutions over ideological purity” and that “as summer turns to autumn, the shadows of crisis are lengthening, looming over the whole country”.

Liz Truss is expected to defeat Rishi Sunak on Monday, taking charge in Downing Street the following day amid soaring energy bills and a worsening cost-of-living crisis.

Starmer wrote: “The appointment of a fourth Tory prime minister in 12 years is no new dawn for Britain. There is no sign that either Rishi Sunak or Liz Truss have grasped the scale of what is facing us, let alone possesses the answers to it.”

Warning that the “centre is not holding” and that things are “falling apart”, Starmer stressed his own pragmatism and desire for progress on energy bills, the NHS and crime.

“I came to politics after a long career. That makes me impatient. It also means I favour common-sense, practical solutions over ideological purity. If I were stepping into Downing Street this week, I’d ensure no one would pay a penny more for their energy bill this winter.”

Labour is proposing a six-month freeze on energy bills at the current £1,971 price cap, funded in part by expanding the windfall tax on oil and gas profits.

“The crisis facing Britain feels different because, this time, we are truly all in it together,” he writes. “It is a crisis of the energy we all need; the health service we all depend upon; the neighbourhoods we all share. The incoming prime minister has to get to grips with them or we will all lose out.”

Starmer, who this week turned 60, earlier told the Mirror that he would use his coming conference speech to set out Labour’s “road map, our plan for Britain and how Labour will give Britain the fresh start it needs”.

He promised plans that include “fixing the short-term problems like the cost-of-living crisis, the National Health crisis and the law and order crisis”, while also looking ahead to rebuilding the economy and tackling the climate crisis.

The Labour shadow health secretary, Wes Streeting, separately accused the Conservatives of intentionally trying to lose the next general election.

In the Telegraph, Streeting said the Conservatives had “concluded there’s no point recruiting medicine trainees because they’re not going to come into work until there’s a Labour government in place. I think that’s recklessly shortsighted.”