Labour's frontbench has offered strong support for the government's HS2 project, as the Commons voted through a bill paving the way for the £42 billion scheme to go ahead.
Ed Balls had faced intense distrust from his own backbenchers ahead of today's debate, as he continued to hint at the possibility of Labour withdrawing its support from HS2 altogether.
The shadow chancellor was absent from today's debate but shadow transport secretary Mary Creagh made clear the opposition frontbench continued to support the project.
"We understand current and future capacity constraints place a brake on regional and city growth... and our support on a north-south line rests on tackling that capacity problem and supporting a 21st century transport infrastructure," Creagh told MPs.
She concluded: "It will fall to the next Labour government, a one nation government, to build HS2 on time, on budget and in the national interest."
The bill debated today provides parliamentary authority for expenditure to pursue the project, including money to pay for property compensation, construction design, ecological surveys "and other essential preparation work".
It passed by 350 votes to 34, although a number of Conservative MPs whose constituencies are directly affected by the scheme rebelled.
"I will try to ensure we get a fair compensation scheme, but I believe this scheme is right for the future of the United Kingdom," transport secretary Patrick McLoughlin said during the debate.
"It is about helping communities, business, the cities of the north and the Midlands to copete on equal terms with London. Nobody begrudges the money we're spending on Crossrail, on Thameslink, but it is time to look at what is going on in the rest of the country too."
The real focus today was on the tensions between the shadow Cabinet and Labour backbenchers, however.
Balls' attitude to the project had been viewed with suspicion by many northern and Midlands Labour MPs, whose seats would benefit from the construction of a Y-shaped network to Birmingham and then Manchester and Leeds.
Balls is worried the scheme could see escalating costs and end up being poor value for the taxpayer. He had previously warned the government should not be handed a "blank cheque" for the project.
With David Cameron threatening that HS2 will have to abandoned if it does not continue to enjoy support from the opposition, many Labour MPs are now deeply concerned by the uncertainty coming from the frontbench.
"Labour's policy – confusingly revealed not by a clear policy process but by a briefing here, an interview there, an aside in a speech over there – [has become] less certain," Ed Miliband ally Peter Hain wrote in an article for Prospect magazine.
"There has even been divisive briefing about who in Labour is in charge of the policy."
A normally sparsely-attended meeting of the shadow transport committee saw over 40 Labour MPs turn up to voice their fears, according to reports.
Cameron sought to portray Labour's policy difficulties over HS2 as another example of Ed Miliband's "weak" leadership in prime minister's questions yesterday.
He said: "Let us just examine what has happened on HS2 this week: the shadow chancellor has been touring the radio studios, telling everyone it will not go ahead; and Labour local authority leaders have been begging the leader of the opposition to stand up for this infrastructure scheme.
"And what has he done? He has cowered in his office, too weak to make a decision."
Today's bill is not the final decision on whether the project goes ahead. That will come next spring, when the government pushes a second HS2 bill through parliament.
This second bill will give the government the legal powers it needs to compulsorily purchase the land needed to build the railway, authorise its construction and 'provide deemed planning permission for the scheme'.