The ban on smoking in pubs, restaurants and other workplaces is set to come into effect in early January after the Taoiseach spoke strongly in favour of it at this week's Cabinet meeting.
Parts of prisons and psychiatric hospitals may be excluded from the ban but the only other outstanding issue is on which day in early January the ban will begin, according to Government sources.
Mr Ahern is understood to have told Cabinet colleagues meeting at Emo Court, Co Laois, on Wednesday that while the new regime would require cultural change, other legislation such as liquor licensing laws had also required such change, but had been successfully introduced.
Comments from Mr Ahern last week to the effect that the timing and other details of the proposed ban had yet to be finalised led to speculation that there could be a compromise on the issue.
However, Government sources sought to end such speculation this week, and said Mr Ahern's contribution at this week's Cabinet meeting made it clear the ban would go ahead.
The Minister for Health, Mr Martin, will introduce amendments to the Public Health (Tobacco) Act 2002 next month defining the workplaces in which smoking is to be banned.
These amendments will be finalised after Mr Martin visits New York later this month.
Mr Martin will be there to sign the UN Convention on Tobacco but will also study the anti-smoking regime there to determine whether some locations in prisons should be exempt from the ban.
The ban is unlikely to be introduced on January 1st, but a few days later, possibly as late as January 6th when the Christmas holiday period ends.
The new regime will require pub owners to erect signs on their premises giving the name of a member of staff to whom customers can complain if the smoking ban is being broken by any individual.