Eurosceptic Tory MPs are pressing David Cameron to toughen his position on the EU and immigration in order to neutralise the threat from Ukip.

The Prime Minister has already promised to set out more details of his proposal to renegotiate looser ties with Brussels.

But he could ‘take the legs’ out of Nigel Farage’s party by campaigning for an ‘out’ vote in a referendum on EU membership if he fails to claw back significant powers, say MPs.

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The PM has already promised to set out more details of his proposal to renegotiate looser ties with Brussels

Senior figures including former Cabinet minister Owen Paterson are expected to call in the next few days for Mr Cameron to make clear he would be prepared to recommend leaving the union if he cannot alter our relationship with Europe.

Andrew Bridgen, one Eurosceptic MP, said yesterday: ‘If we don’t get a satisfactory result for this country, he [Mr Cameron] should say that he will recommend an out vote at the referendum and lead it. I think that will take the legs from under Ukip.

‘He will renegotiate hard for us to stay in the European Union on our own terms, but if we don’t get our “red lines”, control of our borders, control of immigration, and our justice system back, that he would recommend to the British people at the referendum an out vote and lead that campaign.’

Former Cabinet minister Peter Lilley urged Mr Cameron to pursue the idea of a means of restricting numbers coming from the EU in his planned renegotiation of Britain’s membership.

‘It would be absolutely right to have emergency measures,’ he said.

MPs have said David Cameron could ‘take the legs’ out of Nigel Farage’s party by campaigning for an ‘out’ vote in a referendum on EU membership if he fails to claw back significant powers

The Daily Mail revealed earlier this year that Cabinet ministers are examining the idea of an ‘emergency brake’ which could be applied to limit numbers if inflows dramatically exceeded forecasts.

Several Cabinet ministers, including Philip Hammond, Michael Gove and Oliver Letwin, have also already suggested publicly that they would be likely to vote for exit on the current terms.

Another, Sajid Javid, has insisted Britain should have ‘no fear’ of life outside the EU.

Details of the PM’s pledge to renegotiate the UK’s relationship with Brussels were expected in a major speech before Christmas, although allies expect it to come before the autumn statement at the beginning of next month.

Mr Cameron, who has pledged to hold an in/out referendum on Britain’s EU membership by 2017 if he wins the general election, will set out plans to limit the number of European migrants joining the workforce in his speech, Government sources say.

It is expected to propose that Britain seeks to negotiate further curbs on low-skilled EU migrants’ rights to benefits and tax credits. Labour this week hardened its position, saying it wanted to impose a two-year ban on migrants claiming two out-of-work benefits.

Though there is growing support for reform in Germany, the PM is being warned by EU officials that fundamental changes to the right to free movement across the continent would require full-scale changes to the EU treaties that will be all but impossible to deliver.

Figures such as ex Cabinet minister Owen Paterson (pictured) are expected to call in the next few days for Mr Cameron to make clear he would be prepared to recommend leaving the EU if he cannot alter our relationship

Arch-Eurosceptic Sir Bill Cash, a veteran of the battles over the Maastricht Treaty that plagued the Tories in the 1990s, said supporting Ukip was ‘really very self-defeating’.

‘The arguments that Ukip put forward for a referendum, which I’ve campaigned for since the Maastricht Treaty, as it happens, all those years ago, will simply not take place if Ukip deprive us of majorities in the marginal seats and we don’t get an overall majority.

‘You’ll get more Europe as a result as well because the Labour Party want more of an integrationist policy. The whole of the issue of who runs Europe – is it going to be a proper and balanced Europe or is it going to be a German-dominated Europe? – all of those sort of things can only be resolved if the Conservatives win the next general election.’

Tory MP Mark Pritchard, who claims he is ‘more Eurosceptic than Bill Cash’, added: ‘We need as many Conservative MPs returned to Parliament next time because it is only a Conservative government that is going to deliver that referendum on Europe, is going to deliver low taxes, and continue to grow the economy.

‘The fact is that in the majority in the seats, a vote for Ukip is going to help Ed Miliband into Downing Street through the back door.

‘Even though Nigel Farage is a shrewd political operator, he is not a political acrobat and if you try and ride two horses, one on the left, one on the right, eventually you will take a political tumble.

‘I think Ukip are being found out and I think that is partly why you saw a hugely decreased Ukip majority in Rochester and Strood last night.’

TORIES COULD GET MOST SEATS - BUT STILL LOSE IN GENERAL ELECTION The Tories are on course to win the most seats in May’s General Election but will still be short a majority, a new forecast revealed yesterday. Research from Oxford University, compiled using data from opinion polls, predicted that David Cameron will lead the party to take 305 seats in May. The result would mean another hung parliament with the Tories 21 MPs short of a majority and with two seats fewer than in 2010. Labour are set to win 288 seats, up 30 from the last election, with the Liberal Democrats set to lose more than half of theirs, down from 57 to 26. Despite losing the Rochester and Strood by-election, the forecast put the Conservatives in their strongest position since June. Professor Stephen Fisher of Trinity College Oxford said: ‘We now give them a 58 per cent chance of winning the most seats, up from 54 per cent last week. ‘Labour’s chances are down from 46 per cent to 42 per cent. ‘A hung parliament is still the most likely outcome, with a 54 per cent chance, down a touch from 56 per cent last week. ‘The Tories’ chances of a majority are up to 29 per cent [from 25 per cent] while Labour’s are down to 17 per cent [from 19 per cent], their lowest since May.’ Professor Fisher said that it was not yet possible to accurately predict how many seats Ukip will take next May. He predicted that Nigel Farage’s party will win a 13.3 per cent share of votes, ahead of Nick Clegg’s party on 10.9 per cent. The Tories are expected to win the largest share – 35.2 per cent – followed by Labour on 30.9 per cent. Professor Fisher said: ‘The forecasting works by modelling how parties fare over a period of time, so it is still a bit early as there is no history [of Ukip fighting general elections] to help tell us how things will work out.’ He expects to be able to give more detailed analysis closer to May. Current opinion polls and the track record of polls in previous electoral cycles are used to make the forecast, with an allowance for changes in the run up to the election. Yesterday William Hill put both the Tories and Ukip on the same 5/6 odds to win the Rochester and Strood seat at next year’s General Election. The bookmaker was offering 2/5 on Ukip winning five or more seats in May, 4/1 on one or two, and 7/1 on 50 or more. It also had 4/5 odds on two or more further defections to Ukip before the election. Advertisement

So what will this mean come May? Polling expert says another period at political horse-trading seems inevitable

Nigel Farage and his supporters should not overdo their celebrations. The reality is that the margin of Ukip’s victory, at under 3,000 votes, was rather narrower than had been predicted.

In the run-up to Thursday’s vote, pollsters had given Ukip a lead over the Tories of between 9 and 15 per cent, but in the event the gap was only 7 per cent.

Even so, there was a 42 per cent swing to Ukip. If that was replicated across the country in the general election in May – which it won’t be because by-elections are completely different from general elections – Nigel Farage would be Prime Minister, leading his party with an overall majority of 587 seats. Labour would end up with 35 MPs, the Conservatives just six, and the Lib Dems with a lonely one.

The reality is that the margin of Ukip’s victory, at under 3,000 votes, was rather narrower than had been predicted

But the fact is that not only is Ukip incapable of fighting a campaign as intensively on a national scale, it is also hampered by the first-past-the-post system.

Even Thursday’s victor, Mark Reckless, cannot be assured of keeping his seat in May – unlike fellow Tory-to-Ukip defector Douglas Carswell, who, last month, had a lead of 35 per cent over the Tories at the Clacton by-election.

That is why the Conservatives can take some comfort from Rochester, though losing a seat with a near 10,000 majority is certainly a major setback.

For Labour, though, this was a dismal result. Rochester is exactly the sort of Middle England seat that Ed Miliband should be winning if there were a widespread popular wish to see him become Prime Minister. Yet Labour’s vote fell significantly.

In fact, Labour only needed a swing of 10 per cent to take Rochester – but increasingly we are witnessing the extraordinary phenomenon of a Right-wing Ukip eating into Labour’s core vote.

Mr Miliband has a big problem. History tells us that any opposition party that successfully goes on to form a new government tends, in the months leading up to a general election, to win by-elections easily. But that is just not happening. In Rochester, Labour did not even try to win, putting few resources into the campaign.

What makes such negligence all the more remarkable is that this area had a Labour MP throughout the Blair and Brown years.

As for the Liberal Democrats, they have confirmed their decline into near irrelevance.

Once the third party of British politics, the Liberal Democrats under Nick Clegg are now well behind Ukip

Entering Government has turned out to be an electoral catastrophe for them. Once the third party of British politics, they are now well behind Ukip.

With a vote share of just 0.87 per cent, this was their worst by-election result since the Second World War, sinking below the 1.2 per cent they achieved at the Glasgow Camlachie by-election in 1948.

Above all, the Rochester result illustrates the disillusion of the electorate with all the mainstream parties.

But disillusion does not mean apathy. The turnout of 50.6 per cent is reasonably impressive for recent by-elections.

As for what will happen next May, polls carried out earlier this month signalled that no party will achieve an overall majority.

Another period of political horse-trading and either coalition or minority government seems inevitable, with the Scottish National Party, predicted to rout Labour in Scotland, possibly playing a pivotal role.

The most recent polls suggest that Labour would win 312 seats, the Conservatives 283, the Lib Dems 24, other parties 31 – and Ukip none.

But if the SNP advances, the Tories could get most seats (282), Labour 277, the Lib Dems 20, with others including the SNP on 71 – and, again, none for Ukip.

What is certain, though, is that we are witnessing the greatest fluidity in British politics since the 1920s.