Rebel Labour MPs are set to vote for a total ban on smoking in a bid to defeat the government on its current plan.
Fifty-nine MPs, the majority of whom are Labour, have signed a Commons motion calling for "a complete and total ban on smoking in pubs, restaurants and public buildings".
The motion also states: "Any compromise or fudging of this issue by so-called smoke zones will be a recipe for confusion, ambiguity and unnecessary argument and excuses by those not wishing to adhere to both the spirit and letter of the law."
The rebel MPs are expected to receive support from Tory and Lib Dem MPs.
Included in last month's Health Bill were plans to outlaw smoking in pubs that serve food with exemptions for private members clubs, from 2007. The bill is set to have its second reading on November 30.
A spokesman for Action on Smoking and Health (ASH) said: "There's a number of MPs who don't like the drafting of the bill with exemptions for some pubs and clubs.
"We will obviously supply evidence to MPs to show that a total ban would be best. We want the same policy as Scotland, Wales and Northern Ireland. But it's too hard to predict at this stage what the outcome will be."
Exclusive research for The Publican Food Report showed that one in five pubs currently serving food are planning to shut their kitchens when the ban comes in.
Only one in four pubs said they supported the current proposal. Critics have also said a partial ban will increase health inequalities in poor areas.
But Mark Hastings, communications director for the British Beer & Pub Association (BBPA), which has labelled the exemption of clubs "unacceptable" and called for a phased approach, said: "Our objective is to be clear on what the industry wants - and that is a level playing field. We are engaged in a debate and are focussed on presenting the best possible case."
Representatives from the BBPA and the Federation of Licensed Victuallers' Associations were due to give evidence to a health select committee as The Publican went to press.