Most Labour backbenchers want further research on the benefits of ID cards before they are introduced, a poll for the BBC suggests.
Mr Blunkett believes ID cards will help fight against crime
A majority of 101 MPs who responded to the poll favoured the idea, seen by ministers as vital to tackle fraud, terrorism and immigration abuse.
Some 55 wanted more investigation into the scheme, while a third opposed it.
Home Secretary David Blunkett has said he intends to press ahead with a national ID card scheme.
ID cards 'supported'
The idea - which would begin as a voluntary scheme - was supported by most of those who took part in a consultation exercise, including the police, Mr Blunkett said.
ID cards - key facts
From 2007-2008 new passports and driving licences will include biometric data
By 2013 it is estimated 80% of adults will have biometric passports or driving licences
4.6m foreign nationals living in UK among first to register on database from 2007-2008.
Introduction of separate ID cards from 2007/8
Costs of setting up the system over next three years £186m
The total cost will be £3bn
A spokesman for Mr Blunkett accepted the Home Office was still in the process of "winning people over", but he was confident a "clear majority" of MPs would support the proposals.
Under his plan, from 2007/8 all new passports and driving licences will include details such as eye recognition and fingerprints.
Ministers say most people will have one of the voluntary documents by 2013 and then it could be made compulsory.
While people would not be compelled to carry their ID, Mr Blunkett has indicated mobile technology is on the way which could allow police on streets to check people's ID by checking their fingerprints or eye scans.
The home secretary claims the scheme will be vital in fighting benefit fraud, abuse of the immigration system and terrorism.
"An ID card is not a luxury or a whim - it is a necessity," he said.
"I know some people believe there is a sinister motive behind the cards; that they will be part of a Big Brother state.
"This is wrong - only basic information will be held on the ID card database - such as your name, address, birthday and sex.
"It will not have details of religion, political beliefs, marital status or your health records."
Mr Blunkett has claimed independent research shows eight out of 10 members of the public back ID cards.
Britain's most senior police officer, Metropolitan Police chief Sir John Stevens, has also called for a national identity card to be introduced urgently.
But Conservatives have criticised the government plans as "half-baked", while the idea is also opposed by some civil liberty groups.