It was "possible" a Conservative government could scrap the £16 billion cross-London Crossrail scheme, a Tory local government spokeswoman said today.
The party had always been "very supportive" of Crossrail, said Justine Greening, who is standing for re-election in Putney, Roehampton and Southfields.
Asked in a radio interview whether the west to east scheme, due for completion in 2017, would continue, she replied: "I can't give a guarantee that it will continue."
Asked next if the Conservatives could scrap Crossrail she replied: "It's possible, but at the end of the day we've always said that we think it's an important project and actually, the reason this is important is that we want to be responsible so we can't pretend that we can write an entire budget outside of government."
Ms Greening was speaking in an interview with Nick Ferrari on LBC 97.3's The London Debate.
Commenting on the interview, Steve Hart, regional secretary of the Unite union, said: "It is extremely worrying for London that the Tories are refusing to commit to support Crossrail. This project is vital for London's future prosperity.
"In the construction phase, which coincides with this period of recession, it will provide 14,000 jobs for construction workers who would otherwise face unemployment. To scrap a project this large would have a major recessionary impact.
"It is astonishing that Justine Greening should say she will not guarantee that a project of such strategic and economic importance to the capital like Crossrail will continue."
Richard Bourn, Campaign for Better Transport's London campaigner, said: "All three parties need to tell us what they will fund, and what they will cut. The Conservatives need to clarify where they stand on Crossrail. Labour have said in their manifesto that they 'support' some transport schemes without confirming if they'll actually fund them, and the Lib Dems' manifesto was completely silent on Crossrail.
"Voters might be forgiven for not understanding the subtle distinction between 'supporting' and actually funding something."