Emails from thousands of supporters of the protest group 38 Degrees flooded into MPs\' inboxes yesterday, as intense lobbying to win a Commons vote tomorrow on wild animals in circuses entered the final few hours. In an appeal to backers headed \"48 hours to end animal circus cruelty\", 38 Degrees set out the case for action with characteristic brio: \"Beautiful wild beasts – like tigers, lions and zebras – are shunted around the country in trailers, kept alone in small cages, and forced to perform. \"The best circuses have long abandoned this cruel practice and wow audiences with talented acrobats and clowns. If we work together we can persuade our MPs to do the right thing.\" Some 85 per cent of its supporters had agreed to make circus animals its next campaign. As it harnessed the force of its 800,000 supporters, animal welfare groups spent yesterday ringing round MPs to gauge support and provide last-minute briefings. Research by the political communications firm Dods suggests that two-thirds of MPs back a ban, but the Government has ruled one out and Conservative whips are hard at work seeking to ensure the Coalition is not defeated when the division bell rings shortly before 6pm. The challenge is whether campaigners can persuade enough MPs to turn up and overcome the whipped Tory backbenchers, which some of whom such as Zac Goldsmith and Tracey Crouch have have said they will resist toeing the party line. The vote – Parliament\'s first on the issue – is a significant moment in a long battle to remove tigers and lions from the big top and, arguably, the whole animal welfare movement in the UK. The Captive Animals Protection Society, Born Free and Animal Defenders international have been campaigning for a ban for decades. Watching tigers jump onto pedestals has fallen out of favour with the public and the number of circuses using wild animals has fallen from 20 in 1997 to three today. The debate centres on whether the 20 or so remaining can exercise their natural behaviour, and whether they should be performing tricks for human entertainment. The circuses say their animals are well treated and travel short distances. Animal welfare scientists and campaigners say, because of their performances and transience, circuses cannot meet high standards. Training, small enclosures and stress of performing all mean the spectacle should be consigned to history, they say. Constitutionally, a \'yes\' vote tomorrow would achieve this, but campaigners are nervous as well as excited, because they have been here before. In 2006, the Labour minister Ben Bradshaw and, last year, his colleague Jim Fitzpatrick indicated Labour would introduce a ban. On taking power last May, the Coalition began to dither with ministers saying they were concerned about technicalities, such as whether a ban would affect the TV and film industries, and whether to include snakes. By April, it looked as if the Coalition – which had by then blocked improvements to game birds and hens – would finally act. Footage showing the beating of the UK\'s last circus elephant, Anne, had caused a storm and \"senior officials\" briefed a Sunday paper a ban would be introduced \"within weeks.\" Then the RSPCA heard some bad news: Downing Street had blocked the ban. On 6 May, The Independent broke the story, launching a campaign backed by four groups including the British Veterinary Association. We started an online petition – signed by 29,000 people – and commissioned a poll, which showed most supporters of all the main parties backed a ban. Defra announced it could not proceed with a ban because of a legal challenge to one in Austria, and instead proposed a licensing system under which all wild animals would be inspected prior to being authorised for use. The Independent and ADI established there was no such legal challenge and, after Commons Speaker John Bercow granted an Urgent Question debate, the Animal Welfare Minister Jim Paice was ridiculed by furious MPs. Crucially, the Tory MP Mark Pritchard secured a three-hour backbench debate, an innovation designed to hold ministers to account. Conservative whips have been trying to put in an amendment. If the Speaker allows Mr Pritchard\'s wording, all eyes will be on the Commons chamber to discover whether the will of Parliament, or the Conservative whips, has prevailed. Wild animals in circuses Numbers The number of wild animals in circuses is uncertain but, currently, more than 20, including tigers, camels, zebras and pythons, are used by three circuses: the Great British Circus, Peter Jolly\'s Circus and Circus Mondao. Conditions Circus cages and exercise pens give wild animals only 26 per cent of the recommended size of zoo enclosures, according to academic research cited by G Iossa, C D Soulsbury and S Harris of the University of Bristol, in 2009. It found that circus animals spent 90 to 99 per cent of their day in small exercise pens. Many exhibited repetitive behaviour, such as repeatedly pacing.