Three Conservative MPs are undertaking their own ballots of voters on membership of the European Union that are almost identical to those carried by two Ukip defectors.

With Conservative HQ on high alert ahead of an expected byelection defeat to Ukip tomorrow, it emerged that staunch Eurosceptics Peter Bone, Philip Hollobone and Martin Vickers are canvassing constituents on whether they want to be in or out of the EU.

Both of the Conservatives who have jumped ship to Ukip, Douglas Carswell and Mark Reckless, conducted similar exercises before announcing their defections.

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Tory MPs Peter Bone, Philip Hollobone and Martin Vickers have all canvassed their local voters on leaving the EU, just as the two Conservatives who defected to Ukip did

The leaflets being used by the Conservative MPs for their ballots bear striking similarities in design to those used by Mr Reckless.

They are all thought to have been advised by an anti-EU campaigner with longstanding links to Ukip. Chris Bruni-Lowe worked for Mr Carswell in the months before his defection at the end of August, and had previously been employed by Mr Reckless, who jumped ship at the end of September.

Mr Bone, Mr Hollobone and Mr Vickers have all firmly denied any intention to defect to Ukip.

But the revelation of links between their local ballots on the EU and those carried out by Mr Carswell and Mr Reckless will heighten Tory jitters ahead of this week’s Rochester and Strood byelection.

Senior Tories concede Mr Reckless currently appears on course to hold the Kent seat he previously represented for the Tories for Ukip on Thursday.

But they hope other potential defectors will be deterred by the latest poll in the constituency, which puts Ukip on course for victory but suggests the Tories will retake the seat by a narrow margin in next May’s general election.

A new survey by ComRes for PLMR shows 30 per cent of people say they would only vote for their current MP if they stay with their current party

David Cameron, visiting the seat again to campaign yesterday, told any more MPs considering defecting: ‘The point I make to everybody is that these things are entirely counter-productive.

‘If you want a referendum on Britain's future in Europe, the only way to get that is to make sure there's a Conservative government and to make sure that it’s me leading the country and not Ed Miliband.

‘Doing things that distract from that make the chance of an in-out referendum less likely so it’s entirely counter-productive. That's the argument I have made, and the argument I'll continue to make.’

A new opinion poll today showed just one in 13 (7 per cent) adults would vote for their current local MP if they joined UKIP, even though they would not normally vote for Ukip.

It suggests very few MPs can expect to take their voters with them if they choose to defect.

Elin Twigge, deputy managing director of communications firm PLMR, said: 'For any MPs with itchy feet, these polls will be a bit of a wake-up call.'

Mark Reckless carried out a similar local ballot in Rochester and Strood before he defected to Ukip. He is expected to win the by-election in the seat tomorrow

Douglas Carswell, pictured with Ukip leader Nigel Farage, made political history by becoming Ukip's first elected MP in October after defecting from the Conservatives

Mr Bone, MP for Wellingborough, told the Daily Mail that unspecified ‘private donors’ were funding his referendum on EU membership, being conducted jointly with Mr Hollobone, MP for neighbouring Kettering, and Thomas Pursglove, the Conservative candidate for Corby.

‘Yes, the original referendum leaflet was a crib of the one that Mark Reckless did,’ Mr Bone said. ‘The person who has organised it and promoted it was the same guy that did the Reckless one.

‘This was signed off and approved at the highest level of the party a long time before Mr Reckless went to Ukip.’

I believe we should have a pact with Ukip [but] I have never had an discussions with anyone in Ukip about defecting Tory MP Peter Bone

Asked if he was considering defecting, the MP insisted: ‘I deny that 10,000 per cent. I have been a member of the Conservative Party since I was 15. I believe we should have a pact with Ukip [but] I have never had an discussions with anyone in Ukip about defecting.’

In a reference to the charm offensive launched by former Ukip treasurer Stuart Wheeler, who has attempted to woo potential defectors, Mr Bone joked: ‘I haven’t even been invited to lunch. I’ve spoken to Philip Hollobone about it and he has no intention of defecting either.’

The MP added: ‘I would like to see the Conservative Party put forward the policies that will win us the next election: ending free movement of citizens into this country, the PM committing to leading the out campaign if he doesn’t get what he wants in the EU renegotiation, and I would like to see an end to the coalition.’

Mr Vickers said there was ‘absolutely no way, under no circumstances whatsoever’ that he would switch to Ukip, despite conceding his ballot of constituents on EU membership was ‘very similar’ to those carried out by the defectors.

‘This has always been a Eurosceptic part of the world and the idea is to give my constituents an opportunity of expressing a view,’ he said.

Prime Minister David Cameron yesterday insisted the only way to get a referendum on Britain's future in Europe was to vote Conservative, as he campaigned in Richester with Tory candidate Kelly Tolhurst

However, Mr Vickers confirmed he had had ‘an approach’ from Ukip about standing down their candidate in his constituency of Cleethorpes in exchange for Ukip being allowed a free run in neighbouring Grimsby, one of its top targets.

‘From a purely selfish point of view, that would be quite welcome, but I can’t deliver it. Even if the local party was willing to do it, we’re a national party and we will have a candidate in every seat,’ he said.

Stuart Coster, co-founder of the cross-party EU referendum campaign the People's Pledge, said: ‘That more Conservative MPs are consulting their local voters on EU membership in such a similar style to previous Ukip defectors should ring alarm bells in Number Ten.

‘David Cameron needs to reassure his backbenchers with an undertaking that, as a constitutional question about how Britain is governed, he will allow them free rein without party recrimination to campaign for either side in an EU referendum.