Britain's Conservatives worried about rise of UK Independence Party
Tories worried Eurosceptic UK Independence Party could deny them victory in 2015 election
British Prime Minister David Cameron's Conservative Party is increasingly nervous about the threat posed by the eurosceptic UK Independence Party (UKIP), which could split the centre-right vote and deny the Tories victory at the 2015 general election.
The Conservatives have long been plagued by internal tensions over Europe, but much of the talk at their annual conference in Manchester, northwest England, is about the external menace from UKIP.
"They are a real threat," Conservative lawmaker Bill Cash said after a bruising encounter with UKIP's charismatic leader Nigel Farage at a fringe meeting.
Cash is one of the party's most eurosceptic MPs, but Farage dismissed him as "out of touch" when he suggested UKIP back the Tories to prevent handing power to the opposition Labour party. Conservative Mayor of London Boris Johnson repeated the warning, albeit in his usual jocular style: "UKIP if you want to - David Cameron's not for kipping."
UKIP has no MPs but it came third in local elections in May and is polling at 11 per cent, ahead of the Liberal Democrats, the junior partners in the Conservative-led coalition.
The challenge it poses has come into sharp focus ahead of the European Parliament elections, which are in May, when UKIP has a chance of winning the biggest share of the vote with its anti-immigration, anti-European message.
Cameron's ministers are trying to play down the threat and emphasise their own eurosceptic credentials.
The prime minister has promised to renegotiate Britain's membership of the EU and put it to a referendum by 2017 - something no other major party supports.
He made the pledge under pressure from UKIP and restive eurosceptic Tories, but now insists that only the Conservatives are in a position to make it happen. "A vote for any other party won't deliver that referendum," Cameron said.
But worried Tories fear it would only take a small rise in UKIP support to deny them a majority in 2015 and force them once again into coalition - or even out of power altogether.
"At the moment UKIP is destroying the chances of getting a Conservative government, therefore destroying the chances of an in-out referendum," said Peter Bone.
Bone is one of several Tory MPs who advocate an electoral pact with UKIP, and a poll last week found that 22 per cent of Conservative local councillors would support such an idea.
But finance minister George Osborne has rejected the proposal, while Farage ruled it out as long as the Tories are led by Cameron, who famously once dismissed UKIP as a party of "fruitcakes, loonies and closet racists".
However, he indicated he would not oppose deals struck between individual MPs, whether Tory or Labour, who have also been at the receiving end of UKIP's success.
Relations between the two parties were not helped by the decision to deny Farage access to the Conservatives' conference - and even erase his name from the official programme.
The UKIP leader warned the Tories should be worried.
"We are not just a subset, the rump of the Tory eurosceptics - we are a genuine force in British politics," Farage said to cheers and applause.
They revel in their claim not to bow to "political correctness" on social issues, and have won support from voters opposed to gay marriage.
But they have few well-known members other than Farage and last week one of their MEPs, Godfrey Bloom, quit the party after coming under fire for calling a room full of women "sluts", in what he said was a joke.
Farage's spokesman, Gawain Towler, also reignited accusations that UKIP is racist after he referred to a journalist as "of some form of ethnic extraction" in a text message that he mistakenly sent to a photographer.