A bill paving the way for a ban on smoking in pubs and restaurants in England will be published late after ministers disagreed over exemptions.
Ban proposals went out to public consultation in June
Some Cabinet members have clashed over plans for separate smoking rooms and different rules for members-only clubs.
No agreement had been announced by the deadline on Tuesday night, meaning the Health Improvement Bill could not be released on Wednesday as planned.
It is now most likely to be published on Thursday.
'Genuinely difficult issue'
The bill is expected to include a total ban on lighting up in pubs, bars and restaurants which serve food.
Pubs which do not prepare food may have to set aside sealed rooms for smokers, while private clubs could be exempt from a ban.
A Downing Street spokesman said: "Smoking is a genuinely difficult issue ... which people come to from different perspectives."
Any decision to exclude private clubs from the ban would be seen as a victory for Health Secretary Patricia Hewitt's predecessor John Reid, now defence secretary.
Earlier this month the government dropped plans he had put forward as health secretary for a partial ban, which excluded pubs and clubs which did not serve food.
Ministers said consultations had suggested the idea of a partial ban would be too hard to enforce and fail to address health fears.
Culture Secretary Tessa Jowell was seen to be leading criticism of the loophole allowing only "smoking carriage" rooms where staff would not have to serve customers.
Trade unions have also opposed the move, saying that bar staff will still have to inhale smoke when they clean the special rooms.
Liberal Democrat health spokesman Steve Webb said: "It will only increase health inequalities to exempt pubs that do not serve food from this legislation."
Dr Vivienne Nathanson, head of science and ethics at the British Medical Association, told BBC Radio 4's PM programme the proposals were "a huge step forward for the nation's health", but she feared they were "unworkable".
The BMA is still pushing for a complete ban with no exceptions.
A ban on smoking in all enclosed public places will begin in Scotland next March. Northern Ireland has also agreed a ban and one is already in place in the Republic of Ireland.
The plans for England are causing concern among publicans.
The Federation of Licensed Victuallers' Associations, which represents self-employed licensees, says a ban could mean a 10% fall in business.
The British Beer and Pubs Association wants limits on smoking at bars to be phased in.