The report in today's Sun  that Ed Balls has been given the final say over whether Labour supports High Speed 2 has prompted further speculation that the party is preparing to come out against the project. It was Balls who moved to Labour to a more sceptical position when he said in his conference speech that it needed to consider whether it was "the best way to spend £50 billion for the future of our country".
Interviewed today on 5 Live, he warned:
If the case is clear, the benefits are strong, it’s the best way to spend the money and the costs are under control, at that point I would be happy to say we’ll support it. But what I am not going to do is say we support it when the costs are rising, the benefits are unclear and the government are acting like cheerleaders rather than proper stewards of public money. That is not a road I am going to go down.
For the shadow chancellor, the attraction of a U-turn on HS2 is that would allow Labour to outspend the Tories in politically vital areas ("building new homes or new schools or new hospitals") while also remaining within George Osborne's fiscal envelope.
But now, in a dramatic attempt to call Labour's bluff, David Cameron has warned  that the project "can't go ahead without all-party support". At a press conference in Brussels he said:
It [HS2] does have all-party support. We supported it in opposition when Labour were in Government; Labour support it today, as I understand it, now we are in government; the Liberal Democrat party support it as well.
And that is all to the good because these multi-year, multi-parliament infrastructure projects, they can’t go ahead without all-party support – you won’t get the investment, you can’t have the consistency.
In other words, if the opposition comes out against HS2, the government will cancel it and pin the blame on Labour (on the basis that a 20-year project can't be sustained without bipartisan support). This would also allow the Tories and the Lib Dems to suggest their own uses for the £50bn budget, reducing the political advantage to Labour. But if Balls and Miliband believe that they would spend the money more wisely than the Tories, Cameron's intervention may not be enough to save HS2.