Trailing the opposition Labour Party in the opinion polls before a national election expected next year, Sunak will aim to rally Conservative members with a call to action, in all but the last roll of the dice to reset his premiership.

But, as the conference in the northern English city of Manchester draws to an end, his attempt to revitalise his tenure by promising action rather than empty promises has been largely overshadowed by a row over the future of a high-speed train line.

After a year in power, Sunak will take the stage at what could be his last party conference to say he will do things differently, prioritising long-term decisions above short-term opportunism.

“Politics doesn’t work the way it should. We’ve had 30 years  of a political system which incentivises the easy decision, not the right one. Thirty years of vested interests standing in the way of change,” he will say, according to excerpts of his speech.

“Our political system is too focused on short-term advantage, not long-term success … Our mission is to fundamentally change our country.”

His message risks being undermined by a row over the HS2 high-speed railway and his refusal, so far, to announce a decision on whether its second phase with a line to Manchester, the host city of his party’s conference, should go ahead.

Sunak and his finance minister, Jeremy Hunt, have attacked the eye-watering costs of a project that has been dogged by delays and large increases to its budget, which estimates say could hit 100 billion pounds, but both have kept their counsel on whether it will be mothballed.

If it is scrapped or delayed, business leaders say Sunak should be accused of being driven by short-term political gain rather than considering the value a new high-speed train line could offer generations to come.

Hoping to change the narrative, Sunak will also take aim at Labour leader Keir Starmer, a taste of what is gearing up to be an ugly election campaign.

“The Labour party have set out their stall: to do and say as little as possible and hope no one notices. They want to take people’s votes for granted and keep doing politics the same old way,” he will say.

“It is about power for the sake of power. It is in short, everything that is wrong with our politics.”

(Reporting by Elizabeth Piper, Andrew MacAskill and Alistair Smout, Editing by William Maclean)