Former Transport Secretary Lord Adonis has warned HS2 may not happen by the 2020s due to "endless dither and delay" by the Government.
He said plans to get HS2 on the statue book by the end of this parliament could be slowed by dispute between coalition parties ahead of the next general election.
The £33 billion project was given the go ahead in January, with the London to Birmingham line expected to be opened by 2026.
"If infrastructure projects are going to happen they need someone who is going to drive them forward, and that simply isn't present."
An influential group of MPs says the DfT has failed to present 'a convincing strategic case' for HS2.
Campaigners say they hope to put plans for HS2 through the Midlands back to square one as they prepare to go to the High Court tomorrow.
Campaigners from HS2 Action Alliance are heading to London tomorrow to take on the Government at the Court of Appeal.