Tory MPs fear David Cameron is heading full steam into a trap set by Ed Miliband and Ed Balls over the government's plan to fund a multi-billion pound new high speed rail line, warning Labour plans to ditch its support once it is too late for the Conservative Party to do the same.
On Thursday MPs will be asked to vote in favour of a so-called paving Bill for the project, known as HS2, that will connect London to Manchester via Birmingham. The Bill opens the way for the legislation needed to begin construction of the new £50bn railway.
The government has argued the scheme, devised by the previous Labour government, will bring massive economic benefits to northern England and help close the north-south divide.
However critics, including many Tory MPs, have warned it will actually suck even more investment down to London and that the money could be better spent improving rail capacity in other ways - such as between northern cities.
Cameron faces a hardcore of opponents on his own backbenches, including many MPs who will see the line cut through their rural constituencies.
It has been predicted that up to 60 Tory MPs could vote against the government on Thursday. However rebels are downplaying the number, suggesting the figure is likely to be closer to 20.
The recently reshuffled government Whips office is said to be working very hard to persuade backbenchers to support the Bill - with new Whips keen to prove their worth after the embarrassment of the government defeat over military intervention in Syria.
Cameron has admitted the project could only viably go ahead if it has the backing of the Labour Party given its scale. Balls has flirted, confusingly, with the idea of dropping his support - citing the high cost - but he is expected to throw its support behind the paving Bill.
Conservative Andrew Bridgen, who has been a sharp critic of HS2, has warned Labour only intends to vote in favour of the paving Bill on Thursday to ensure the Conservative Party is fully committed to HS2 by the time of the next election in 2015.
"They want us right down the track," Bridgen said. "Labour will support the Bill going forward so we are fully committed. Labour want to leave us shunted into political siding, very exposed. They will leave the Conservative Party in a very vulnerable position, damaged in the Shires and the marginals."
He told The Huffington Post UK: "The support of the Opposition is the rope's support to the hanged man. Labour are giving us enough rope to hang ourselves. It's a great shame to be run over by a train you can see coming a mile off."
Cameron's former Welsh secretary Cheryl Gillan has also publicly warned that it would be too tempting for Labour to drop the project in advance of the election and use the money to promise funding for vote winning policies across the country.
"You can't tie Labour into it. It opens up a political opportunity. I think this will be too easy for Labour to blink and drop it she warned, before the party suggested it may do just that. "You've got an awful lot of money for Labour to play with."
Bridgen predicted Ed Balls would use £14bn freed up between 2015 and 2020 if Labour dropped HS2 to fund a campaign "war chest" for the next general election to "buy votes" in Northern cities.
The North West Leicestershire MP said there was "no business case" for the new line. "All it does it draw money and talent into London. By the time it's completed technology will have moved on. Business people will have video conferences a lot more and travel less."
Yesterday Nick Clegg indicated that support for the high speed rail link between London and the north would be a red line in any coalition discussions with Labour at the next election. Asked if he would ever compromise on HS2 in a future government, Clegg told reporters at a press conference in Westminster: "No. I was up in Sheffield yesterday talking to business leaders and they are absolutely appalled at the way in which Labour appears to be betraying the north."