Keir Starmer is to formally revive Northern Powerhouse Rail this autumn with an announcement expected before the Labour conference, as a major demonstration of Labour’s commitment to northern infrastructure.

Sources said the speech would be delivered by Starmer and Rachel Reeves as they attempt to show their commitment to Labour’s former heartlands across the north of England, where Nigel Farage’s Reform UK is eyeing significant gains at the next general election.

Government advisers are planning to time the announcement before Labour conference on 28 September, with the aim of boosting the morale of backbenchers after a series of damaging U-turns.

The transport secretary, Heidi Alexander, is expected to make the rail project a key theme of her conference speech. A government source said the announcement was likely to take place before then but that the timing was not yet confirmed.

Political and industry figures in the north of England have urged Starmer for over a year to revive the Manchester leg of HS2 and to build Northern Powerhouse Rail (NPR), an east-west connection linking Liverpool to Hull.

NPR is seen by some as critical to rebalancing the UK’s economy as it would connect potentially five of Britain’s major cities – including Leeds, Bradford and Sheffield – on a route that for decades has been choked by trundling old trains and the overloaded M62. A DfT source said the exact route had not yet been formally agreed.

The NPR plan requires part of the HS2 construction between Crewe and Manchester to go ahead, raising hopes that ministers would also commit to some form of HS2 running to Birmingham and London.

Andy Burnham, the Greater Manchester mayor, has lobbied Starmer’s government extensively for both new rail networks. He has also warned, however, that any HS2 service that was high speed to the Midlands and a slower service in the north would be a “monument to the British mentality”.

Hopes about imminent rail plans were raised last month when Heidi Alexander, the transport secretary, left open the possibility of reprising a form of HS2 to Manchester, a route killed off by Rishi Sunak in October 2023.

The government spent more than £500m buying up land and property north of Birmingham under the original plans of HS2 travelling north along two legs, one to Leeds and the other to Manchester.

Alexander confirmed last month that the land for the Leeds leg would now be formally sold off after that part of the project was axed by Boris Johnson in 2021.

However, she left open the prospect of a new rail project on the Birmingham to Manchester land, which is still owned by the government.

Reeves said in June that she would “take forward our ambitions” for NPR in the coming weeks and it appears on the infrastructure pipeline quietly published by the Treasury last month.

While NPR has effectively been costed by the Treasury, the huge sums involved in funding a northern HS2 mean that it would almost certainly only be viable through a form of private investment.

Starmer and Reeves began a series of meetings earlier this month to prepare the budget, likely to take place in mid-to-late November. They will begin to prepare the ground for tax rises and reforms from next month.

Government strategists believe that the budget should be a moment to argue that Britain must now make serious choices on growth and productivity. They say Starmer must forcefully rebut the charges that the poor state of the economy is down to individual tax and spend choices, saying it is instead a sign of the weakness of the economy’s fundamentals.