Former Chancellor George Osborne has called on the government to build high-speed rail lines across the north of England, from Liverpool to Hull.
Mr Osborne, who spearheaded the “Northern Powerhouse” initiative when in government, asked for the commitment in an article in the Financial Times.
He admitted “it will not be cheap”, but said it would “transform” the economy.
The government said it was “investing billions of pounds” to “better connect communities” across the north.
The Northern Powerhouse Partnership – chaired by the former Tatton MP – is launching a campaign for the new-high speed connection this week, starting with a line across the Pennines.
This plan for “HS3” would follow on from the existing HS2 scheme – a planned line linking London and Birmingham, that will split into two branches to Manchester and Leeds.
The partnership wants the government to redesign the second phase of HS2 to “remodel” four junctions, which will then connect to their rail proposals.
Writing in the FT, Mr Osborne said “this new railway would transform the northern economy”.
“It would bring seven million extra people – and three times the number of businesses – within a 90-minute journey time of one of the northern cities.”
He said the estimated cost of the Pennines line has been put as high as £7bn, but the investment could be spread over many years and the transport budget was built to take in such large projects.
“There is no geographical reason why this cannot happen,” wrote Mr Osborne.
“The distance between Manchester and Leeds is shorter than the length of the Central line on the London Underground.
“The Northern Powerhouse Rail fits with [Theresa] May’s stated objective of building an economy that works for everyone.”
The campaign follows anger from both local authorities and businesses after the government scrapped the planned electrification of railway lines in Wales, the Midlands and the North.
Days later Transport Secretary Chris Grayling backed proposals for Crossrail 2 – a north-east to south-west railway in London.
A spokesman for the Department for Transport said the government had already made a commitment to Northern Powerhouse Rail, giving £60m to Transport for the North to develop plans – adding: “[We] look forward to working with them once proposals are submitted later this year.”
“We are also investing billions of pounds across the north of England to better connect communities, build the Northern Powerhouse, and deliver improved journeys right across the region,” he said.