High speed rail between London and Birmingham might not be achieved in the 2020s because of "endless dither and delay" by the Government, former transport secretary Lord Adonis has warned.
The Labour peer said plans to get HS2 on to the statute book by the end of this parliament could fall victim to wrangling between the coalition parties ahead of the next general election, scheduled for 2015.
The highly-controversial £33 billion network was given the go ahead in January, with a line between London and Birmingham expected to open by 2026.
Urging Prime Minister David Cameron to get a grip on the issue, Lord Adonis said: "If infrastructure projects are going to happen they need someone who is going to drive them forward, and that simply isn't present.
"We are already on the second transport secretary since the election, the Transport Department has had three permanent secretaries in the last two years. There has been endless dither and delay."
Lord Adonis, an architect of the high speed rail plan in the last Labour government, said there were delays to the consultation on compensation for householders affected by the project and in publishing the route north of Birmingham.
He told BBC Radio 4's Today programme: "I think there is now a very good chance that the legislation won't pass in this parliament. It could well get caught up in all the politics leading up to the next election, which I think given the state of the coalition could lead to a very significant further delay and it means that we may not see HS2 now in the 2020s."
Transport Minister Theresa Villiers insisted the project would be delivered "as swiftly as possible" but the Government would "not be rushed".
"This is a major project which will have a significant impact on the future of the country and it is imperative that we get it right.
"We will ensure it is delivered as swiftly as possible but we will not be rushed - all relevant evidence needs to be properly considered, including the views of communities potentially affected by the line, and we will be doing this within the timeframe we set out soon after the Coalition entered Government."