A political consensus has emerged to invest billions of pounds to create a "great" city constellation in the north of England, George Osborne has claimed, promising to support a call from five northern cities for a £15bn investment over five years in science, transport and infrastructure.

The chancellor was speaking in Manchester where he is to meet the leaders of the five cities to discuss their report calling for greater connectivity between them.

He promised that the coalition's autumn statement would include plans for major investment in the north, saying: "Individually the cities are great, but collectively they are weaker than the sum of their parts".

His officials stressed that his support for the principles and direction of the plan did not stretch to a commitment to the £15bn investment plan proposed by the five cities, however.

The proposals from Leeds, Liverpool, Manchester, Newcastle and Sheffield were imaginative, Osborne said. They include increased road capacity, a trans-Pennine rail route, better access to Manchester airport, modernisation of rail rolling stock and addressing pinch-points on the rail network.

Asked for a response to the proposals, Osborne said simply "yes", adding that he would make a major commitment to economic growth in the north before December.

Aware of the Conservatives' weakness in the north and eager for a more optimistic vision for his party's manifesto, Osborne has embraced the thinking of northern local government leaders, and they in turn are happy to use the pre-election period to bank promises of investment from all political parties.

Labour, aware that many of the ideas originated from its own party, accused Osborne of coming to the issue too late in the lifetime of the coalition and challenged him to make specific commitments.

Osborne restated his promise that the cities should be run by elected mayors with real civic powers, a proposal voters rejected in a number of referendums two years ago.

He said the overall aim was "to end the imbalance in the UK economy so our success is not wholly dependent on the global city of London, so we have across the north of England individual cities that are better connected, have a better quality of life, and are able to create".

Osborne said he did not see a conflict between already tabled plans to build a second Crossrail in the south or a major transport link between Liverpool and Leeds.

The real public expenditure choice facing the UK, he said, was between investment in big infrastructure and "continuing to spend money on welfare payments that are not generating either a real economic return and at the same time are trapping people in poverty".

It was about trying to capture a larger vision than narrow cost-benefit economics, he said.

"If we can bring these northern cities together with these individual transport schemes that create a collective northern powerhouse then you might achieve something really important in our country that has eluded successive governments of different colours – a real improvement of economic wealth in the north.

"If the north's economic GDP grew at the rate of the average GDP of the UK we would add over £50bn to our economy by 2030. That is a massive benefit for people in the north – over £1,600 per person."

Osborne said he was trying to sort out problems that stretched back decades, and were not just a result of the financial crash. Over the years, efforts to improve the northern economy had been sporadic, piecemeal and not totally coherent, he said.