Andy Burnham, the mayor of Greater Manchester, has urged new Tory voters in the north of England to be wary of Conservative promises to invest tens of billions in the region’s infrastructure.

Small print in the Conservative manifesto allowed for up to £100bn in additional capital spending over the next five years, £78bn of which has not yet been allocated. To date, £22bn has been earmarked for specific projects, such as £500m to reopen old train lines, £2.2bn on a public sector decarbonisation scheme, £4bn on flood defences and £2bn on potholes.

An unnamed “senior Tory” told the Sunday Times that the remaining money needs to “show the voters in the red wall seats that they have something to show for voting Conservative”. The new MPs already have an extensive shopping list of demands they promised to voters during the campaign, including rail links to remote ports, new nuclear reactors and train stations.

Speaking in Tony Blair’s former constituency of Sedgefield in County Durham on Saturday, Boris Johnson promised to “level up” the UK by “investing in better infrastructure, better education and fantastic modern technology” across the country.

He will be under pressure from northern businesses and civic leaders to spend over half of the money – £39bn – on Northern Powerhouse Rail, a new TransPennine rail link from Liverpool to Hull which doesn’t have stops in many Conservative constituencies.

Burnham welcomed Johnson’s sentiment but said such promises were easier to make than deliver.

“If there is a positive to take from last week, and it’s a big if, perhaps it’s that the political classes are finally addressing the issues the north has long suffered from,” he said.

“But I would warn people to be wary of glib commitments around infrastructure because they are decades off. And sometimes these are easy pledges for politicians to make but they never come true because they are beyond the political cycle.

“The issue is people’s lives in the here and now. Clearly the north needs infrastructure but that doesn’t tick the box for the north, which is the way the Westminster world is portraying it now.”

Burnham said he would like the government to commit funds now to reduce homelessness and to subsidise bus services so they are as cheap as in London. Each month he donates 15% of his own salary – £1,375 – to try to cut rough sleeping in Greater Manchester, and his Bed Every Night scheme was part-funded by more than £300,000 from then Manchester City player Vincent Kompany.

The army of new Tory MPs in the north of England have already started to demand investment in their patches. “As a newly elected member for the north-west of England I am going to be fighting very, very hard to get funding here. We need rail infrastructure, we need road infrastructure,” Andy Carter, the new MP for Warrington South, told the BBC’s Sunday Politics North West show.

Many new parliamentarians seem to believe in growing public spending rather than reducing it, reversing the party’s dedication to austerity over the past decade. James Daly, who won Bury North from Labour by just 105 votes, said he wanted “more money for public services, more money into our brilliant schools, more money into NHS services and more police on our streets”.

Mark Jenkinson, who won the west Cumbrian seat of Workington, wants the government to build small new nuclear reactors in the region and has promised to lobby for better road and rail links to the ports in Workington and Silloth.

Ian Levy, whose win in the Northumberland seat of Blyth Valley gave the first indication on election night that the “red wall” was crumbling, wants the return of passenger rail services to the constituency.

Graham Stringer, the Labour MP for Blackley and Broughton in Greater Manchester, warned that an increase in Conservative MPs in the north wouldn’t necessarily equal more investment. “We had more Tories in the north of England in the 1980s and that’s when our infrastructure was seriously damaged,” he told the BBC.

Transport for the North, the statutory body which advises government on transport in the region, wants the government to fund its £70bn plan to upgrade road and rail connections, including £39bn for Northern Powerhouse Rail. “Now is the time to advance that northern agenda in the national interest. The prime minister must now deliver,” said chief executive Barry White.

“We’ve been encouraged by promises to fully commit to Northern Powerhouse Rail, and invest in our strategic and local roads. That, and tackling the challenge of making our networks greener and more inclusive, will be critical in the coming months and years,” he said.

A source close to the chancellor, Sajid Javid, said no decisions had yet been made on how to spend the £78bn. “Broadly what we are looking for is projects that will improve productivity, offer good value for money and make a real difference to people’s lives,” they said.