Liz Truss has vowed to overturn Boris Johnson's decision to scale back a huge railway scheme in an attempt to woo voters in Northern England.
The Foreign Secretary, who polls suggest is leading the contest to become the next PM, has pledged to fully back Northern Powerhouse Rail (NPR), a move that will cost nearly £25 billion.
But she insisted the country could afford to pay for the project despite proposing sweeping tax cuts in her pitch for Number 10.
Last year Mr Johnson sparked anger when he announced that funding for NPR would be slashed by £24.9 billion - with existing routes replaced rather than building a new line.
At the time the government claimed NPR scored lowest on "affordability and value for money" - even though civil servants said it would provide "the greatest increase in connectivity and capacity" of all considered options.
It comes as Ms Truss and rival Rishi Sunak prepare to make their pitches to voters in Leeds, where a hustings event will be held later today.
Ms Truss today insisted she is "completely committed" to her plan for the new high-speed rail connections.
This would mean tens of billions of pounds of new infrastructure investment and new high speed connections running from Liverpool to Leeds via Manchester and Bradford.
The wannabe Prime Minister told reporters in Leeds: "I grew up in Leeds, I know how poor the transport is and frankly, it's not got much better since I was a teenager getting the bus into Leeds city centre.
"What I want to see is really fantastic rail services, better roads so people are able to get into work.
"I'm clear it is absolutely crucial for the future of the north of England."
Asked how she would afford the scheme, given the vast tax cuts she has pledged, Ms Truss said: "The taxes that I am cutting are affordable within our budget.
"By creating new low tax investment zones in places like West Yorkshire, by enabling the post-Brexit reforms to take place, unleashing more investment from the city, we will grow the economy faster - that will bring in more tax revenue, and that will enable us to afford those projects".
Ms Truss was given a boost after Tory MP Jake Berry, who chairs the Northern Research Group, announced he was supporting her leadership bid.
"Today I'm announcing that I'm backing Liz because she's the person with energy to bring action and delivery to make sure we level up our United Kingdom," he said in a video shared on Twitter.
This evening's hustings in Leeds comes after mayors from across the North of England wrote to the two contenders to express concerns about the Government's plans for northern transport.
Andy Burnham, Tracy Brabin, Steve Rotheram, Oliver Coppard and Jamie Driscoll called on the winning candidate to meet with them to agree a "better way forward for the North".
"This is a critical decision that will affect the lives of generations of Northerners to come. We owe it to them to show the highest possible ambition for what the North of England can be in the future," they wrote.
Tonight's event will be the first of 12 sessions for party faithful to quiz the final two candidates before voting for the next party leader and prime minister closes on September 2.
The two-hour hustings will be broadcast on LBC radio from 7pm and hosted by presenter Nick Ferrari.
Ms Truss took a veiled swipe at Mr Sunak, who is the MP for the North Yorkshire seat of Richmond, when she was asked whether he was as committed to the rail project, saying: "The thing about me is I'm prepared to take on the Whitehall orthodoxy, I'm prepared to challenge the groupthink that has, over decades, not put enough investment into this part of the country."
She will be painfully aware that new YouGov polling suggests Mr Sunak has a significant edge over her among swing voters - even thought both suffer from "considerable" unpopularity with the public as a whole.
The latest poll is a boost for Mr Sunak, who has been accused of flip-flopping over economic policy, with Boris Johnson this morning taking a swipe at his plans to slash VAT from energy bills.
Former chief whip Mark Harper, who is backing Mr Sunak, defended the ex-chancellor's decision to announce his pledge to cut VAT from domestic energy bills for a year at this stage in the race.
Asked why Mr Sunak did not open his campaign with those plans, Mr Harper told BBC Newsnight: "He's announced it because it looks like the energy price cap may rise higher by several hundred pounds than we had thought it would.
"And he's always said very consistently, that if he needed to do more, he would.
"And he's announced this particular policy now partly so that those people listening to this programme at home will have some peace of mind that, if he were elected prime minister, that actually he is always going to have their back in the same way he did during the pandemic."
