Legislation needed to extend the new high-speed rail line HS2 from Birmingham to the north of England has been delayed by a year, it has been reported.
The blow comes as the man spearheading the second phase of the huge infrastructure project has quit the role to take on a new job in Canada.
The Department for Transport (DfT) said it was important that the £55.7 billion project "takes full account" of Northern Powerhouse Rail, the scheme to boost rail connections from east to west across northern regions.
The second phase of HS2 will see high-speed services leave Birmingham and head to Cheshire and the North West and Yorkshire via the East Midlands.
The first phase between Birmingham and London is due for completion in 2026 and the second phase in 2033.
Transport Secretary Chris Grayling announced last summer that the tabling of a bill in Parliament for phase 2b, which runs from Crewe to Manchester and Birmingham to Leeds, would take place in 2019.
But the Government is preparing to pause this until 2020, according to a report in The Times.
The DfT would not confirm the delay but issued a statement, saying: "In order to maximise the huge potential of HS2, it is important to make sure it takes full account of the emerging vision for the other transformative project of Northern Powerhouse Rail.
"Phase 2b of the railway will connect the great cities of the North to boost jobs, housing and economic growth and remains on track to open in 2033.
"We will update Parliament as part of our consultation this autumn."
In a separate announcement, the DfT said that Paul Griffiths, managing director of phase two of HS2, is to leave the post at the end of this year.
He has been appointed as the new program director of the $40 billion Metrolinx program in Toronto, said to be the largest public transit investment in Canadian history.
Mr Griffiths joined HS2 in 2015 and has been responsible for working with central government and local stakeholders to plan and develop the route for phase two.
He becomes the latest senior figure to leave HS2.
In 2016, chief executive Simon Kirby announced he was stepping down to take a newly created role with Rolls-Royce, eventually being replaced by Mark Thurston who previously worked on the £15 billion Crossrail project in London.
Last year, director general David Prout quit his post for a senior role at the University of Oxford, to be followed a few months later by chief financial officer Steve Allen.
Mr Allen resigned after a damning report was published by the National Audit Office into staff redundancy payments related to the team's move to Two Snowhill in Birmingham.
And earlier this year, Sir David Higgins stepped aside after serving two terms as chairman, to be replaced by Sir Terry Morgan, one-time chairman of the National College for High Speed Rail which opened in Birmingham last year.
Mr Griffiths said: "Seeing HS2 move considerably closer to reality has been a privilege and will always have a special place in my career.
"HS2 is vital for the future of Britain and I will always be proud to have been part of its development."
Mr Thurston added: "Phase two has come a long way under Paul's leadership.
"We are grateful to Paul for the progress he has made with phase two and wish him and his family well in their new adventure."