Former Treasury minister Lord O'Neill has blasted Prime Minister Theresa May's handling of the Northern Powerhouse, warning that May's government is not "embracing" the project.
The Northern Powerhouse policy was created by former chancellor George Osborne, with ex-Goldman Sachs banker Jim O'Neill recruited to help.
Osborne has since set up a think tank to continue to support the plans, which are focused on providing better connections between Manchester, Leeds, Sheffield and Liverpool.
However, O'Neill - who quit government in September - today hit out at the current government's dedication, branding May's stance "disappointing".
"They seem to be tolerating, rather than embracing, it," O'Neill said.
Speaking at the Prosperity UK conference in London, he said May and her ministers are effectively transmitting the message that the project is not a priority, and limiting enthusiasm in the private sector to support it.
"Governments in general around the world aren't the greatest at spending money efficiently, so what they need to do is demonstrate that it's really important and be so convincing in persuading the private sector to do it for you," O'Neill said.
"I don't understand why the current machine doesn't quite get it. And I've travelled to China and the Middle East and all over the place and people love the Northern Powerhouse stuff, and they would be very intrigued by the Midlands Engine if the government was more noisy about that, too."
O'Neill was speaking on a panel alongside Midlands Engine and Standard Chartered chairman Sir John Peace, who made a plea for more investment in the roads and rails at the heart of the country.
Noting that 80 per cent of the country's freight travels through the Midlands, he said: "If you want economic growth, then the question is can we afford not to invest?"
Peace added that while May's industrial strategy green paper represented "a good start" in developing the UK's cities beyond London, he warned that plans cannot simply be cut and pasted between different locations.
"If you are going to rebalance the economy then you have got to take that industrial strategy and adapt it to each particular part of the country," he said.