The £6.2bn overhaul of the NHS IT system could be undermined by declining support among doctors, a survey says.
The upgrade will allow patients to book hospital appointments electronically
Just one in five GPs are enthusiastic about the upgrade - down from more than half last year.
Support among hospital doctors fell from 75% to 51% during the same period, medical pollsters Medix found.
The 10-year IT programme will give patients electronic health records and allow them to book hospital appointments of their choice online.
The findings come after a National Audit Office report warned last month that the government had failed to engage with GPs over the upgrade which is supposed to revolutionise the NHS for the 21st century.
And last year Computer Weekly magazine said the costs of the National Programme for IT could exceed £30bn.
The Medix poll of 900 doctors, co-sponsored by the Guardian and Computer Weekly, also found GPs felt the new system was less important than they did a year ago.
And 70% of GPs and 42% of non-GPs felt the electronic records would be less secure than paper-based systems.
And just 5% of all doctors said consultation on the upgrade had been adequate.
Medix concluded: "It will be a major challenge to overcome the distrust and cynicism that seems to be replacing enthusiasm in the minds of many doctors. That challenge must surely be addressed urgently."
Dr Paul Cundy, chairman of British Medical Association's GP's committee on IT, told BBC News the findings were "deeply depressing".
"At the end of last year GPs were given a demonstration of how the new system would work and it was clear it was not good enough.
"It was meant to be an all singing, all dancing system but it is not up to scratch.
"Since then GP enthusiasm for the project has plummeted."
A spokesman for the NPfIT accepted there needed to be more consultation with doctors.
"The national programme recognises that clinical engagement is essential.
"Medix says that a reinvigorated engagement programme may well rebuild enthusiasm for NPfIT which has the potential to be a success. That is exactly what we have embarked on.
"We know there has been some discontinuity in our clinical engagement.
"But we have recently adopted a new approach, appointing a number of senior clinicians to lead this engagement work."