Identity cards are opposed by the Tories and Lib Dems
Plans for a large scale rollout of ID cards to British nationals appear to have been delayed for two years - beyond the next general election.
The government had planned to start issuing "significant volumes" of ID cards alongside passports from 2010.
But leaked Home Office documents suggest that it has now been put back to 2012. The Conservatives say the plan is "in the intensive care ward".
The government said it always planned to introduce the cards "incrementally".
While foreign nationals are due to start getting ID cards this year, the timetable for UK citizens over 16 has already slipped and the first ones are not expected to start being issued until next year.
From January 2010 everyone getting a passport will have to get an identity card as well, according to existing plans drawn up in 2006.
When he was prime minister, Tony Blair said that legislation to make it compulsory for all Britons to get an ID card - not just those getting a passport - would form a "major plank" of Labour's next election manifesto.
But the scheme has met fierce criticism from the Conservatives and Liberal Democrats on cost, effectiveness and civil liberties grounds.
Home Office documents, drawn up in December and leaked to the Conservatives this week, set out an illustrated timeline for introducing biometric ID cards.
It includes the "Borders Phase I" introduction of ID cards for foreign nationals, which will begin later this year.
Then it indicates that people in positions of trust - like security guards - will be issued with cards in 2009.
But the "Borders Phase II" wider roll-out to all UK citizens will not begin until 2012, the document says.
Shadow immigration minister Damian Green told the BBC: "It's clear that there are enormous practical difficulties in putting 50 different pieces of personal information including addresses of 60 million British citizens plus lots of foreigners into a single database."
"I think the reality is just beginning to bite ministers on this, so this delay is the first sign of reality intruding, let's hope there are more to come."
And Lib Dem home affairs spokesman Chris Huhne told the BBC: "It seems to me we are shaping up for another absolutely classic government IT fiasco.
"If Gordon Brown actually had the courage of his convictions and stopped dithering and delaying for a moment he would recognise what he began to recognise last week in his ambivalence towards this scheme and scrap it now."
ID cards have also come under fire from experts, including Professor John Salt, of University College, London, who has advised the government on migration trends.
Asked by a House of Lords Committee on Tuesday if ID cards would help curb illegal immigration, Professor Salt said: "No, if they are capable of being forged - and that is probably likely to happen."
Fresh questions about the identity card scheme have been raised by the loss in recent months by government of data held on CDs and laptops relating to millions of people.
Home Office minister Tony McNulty told the BBC on Wednesday that he would not comment on leaked documents but "the identity card strategy remains in place".
Mr McNulty said: "This year ID cards will be rolled out for foreign nationals with visas, by 2009 we will start rolling them out with the 'second generation' - the biometric passports - and that's as was in the schedule in 2006 and remains the case."
"We always said this would be by increment... and that's what the strategy said in 2006, and that's what this reflects."
There have been reports that Gordon Brown had cooled on the idea of compulsory ID cards for UK citizens, saying it was only an "option" that would be the subject of a Parliamentary vote.