The public body behind Manchester-to-London rail link HS2 is spending up to £2m on polling amid widespread public opposition to the scheme.
HS2 Ltd has signed a four-year deal with pollster Ipsos Mori worth as much as £1.96m, which began earlier this month, public records show.
One industry insider said the deal was among the biggest they had ever seen for a survey from a taxpayer-backed organisation.
The contract has sparked outrage among critics of the mega-project who are already furious at its spiralling £106bn budget.
HS2 is due to start operating in 2028 and will offer ultra-fast connections between the North and London. But it is unpopular with swathes of the public, with 42pc of Britons against it and 32pc in favour, according to a Yougov survey earlier this month.
Baron Berkeley, who resigned from an official review of the scheme and produced a dissenting report that sharply criticised it, said: “The cost of HS2 was already high, while there's been a massive reduction in demand for rail.
“It’s remarkable they’ve spent this money to persuade people the project hasn't failed.”
Harry Fone, of the Taxpayers’ Alliance pressure group, said: “It’s ridiculous that HS2 is lavishing millions of pounds of taxpayers’ money on pointless polling.
“With total costs in the hundreds of billions and this latest round of spending, it’s clear the project’s budget is off the rails.
“If they won’t do the right thing and scrap the project, ministers should at least keep a close eye on the costs.”
A spokesman for HS2 claimed the deal is in line with other contracts for polling, and that the end bill may be lower than the initially agreed price.
But polling industry experts were surprised by the figure.
A senior insider said: “£2m is a lot of money for anyone to be spending on polling, and it’s very rare for a single project to be costing so much money.”
A spokesman for HS2 said: “HS2 Ltd is required by the Government to conduct regular surveys and other research with communities living along the line of route and the general public.
“This ensures we are communicating properly with impacted communities and the general public in a clear and timely manner and can understand and act on their concerns.”
Ipsos Mori and the Department for Transport did not comment.