Representatives from the British Hospitality Association and the Bingo Association have joined forces with a group of MPs to call for a total ban on smoking.
The Health Bill, which will introduce the smoking ban, is due to return to the House of Commons for its second reading today.
Some 81 MPs - including 50 Labour backbenchers - have signed a parliamentary motion calling for a "total ban on smoking in pubs, restaurants and public buildings".
Labour's Frank Dobson, Liberal Democrat Steve Williams and Conservative Sir George Young all spoke out against the exemption ahead of the reading.
Dobson said an amendment pushing for a total ban would be tabled by Labour MPs later in the parliamentary process, meaning any potential rebellion is unlikely to take place today.
Campaigners claim that the proposed partial ban would be unworkable and will lead to unfair competition between venues.
In evidence to the Commons' Health Committee earlier this month, Bob Cotton, chief executive of the British Hospitality Association, said that the association was opposed to the proposed exclusion from the ban of pubs that did not serve food, and private clubs.
"Pubs that serve food may well see their trade seep away into the local non-food pub - or to the local working men's club - thus encouraging exactly what the government is committed to fighting: rising alcohol consumption and binge drinking - not to mention excessive smoking," he said.
The BHA estimated that 100,000 staff in the hospitality industry would still be exposed to passive smoke.
Cotton said: "How can separate smoking areas protect staff who are obliged to service them? It seems extraordinary that the government's own health department is considering allowing such a development given the medical evidence on the dangers of passive smoking.
"As it stands at the moment, the proposal is unworkable and will lead to enormous difficulties in interpretation and serious confusion. It is a non-decision."
