Analysis : The party is targeting a handful of constituencies – primarily that of Nigel Farage – in its to attempt turn doorstep dissatisfaction into parliamentary seats

The Conservative party has spent the last few years trying not to talk about Ukip, hoping it would fade away or self-combust. One senior Tory minister even refers to the party’s leader, Nigel Farage, in private as the “F-word” who cannot be named.

But six months ago, after the defection of two Tory MPs, David Cameron decided to confront the issue from a tactical point of view. Those who go to bed with Farage are at risk of waking up with Ed Miliband, he warned at the Conservative party’s autumn conference. It was an admission that Ukip could cost him the election.

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At the same conference in Birmingham, Lynton Crosby, the Conservative campaign chief, summed up what would be the party’s election approach in a private meeting with activists. Ukip was a minor party to be “dealt with” without attacking its voters, he said.

“We say they’re incompetent, but not that they’re wrong,” explains one Tory adviser. In other words, MPs and activists are allowed to cast doubt on Ukip’s credibility as a political force, highlight gaffes by rogue candidates and warn that they could let in Labour. But there was to be no diminishing the views of Ukip supporters who have turned to Farage in frustration over immigration and the European Union.

Having attempted to dispel both policy issues by promising an EU referendum and curbs on migrant benefits, the election campaign this year was to be a straightforward clash between Cameron, focusing on the economy, and Miliband, on the NHS, with Farage an increasing irrelevance as the weeks ticked by.

However, the predicted squeeze in support for Ukip has taken longer to materialise than many nervous Tory MPs had hoped. Since January, the Guardian’s poll of polls has suggested support for Farage’s party may be down a point or two. But the overall picture still implies Ukip has around 14% of the vote.

Unless the polls move more, this causes two problems for the Conservatives. The first is the direct threat of a Ukip victory in a handful of mostly Conservative seats, such as South Thanet, Boston and Skegness, Castle Point, and Thurrock. These – along with a couple of Labour targets – are where Ukip is directing most of its available financial muscle and ground troops, as well as organising visits from Farage himself. The Tories have more money but Ukip has a narrower range of targets.

The second more pressing issue for Conservative HQ is the dozens of marginal seats where MPs are trying to fend off Labour challengers and take on the Liberal Democrats. This is where the leakage of support to Ukip matters the most and could lose Cameron his place in No 10.

Tory MPs campaigning in these seats have the difficulty of trying to win over voters at both ends of the spectrum: the Labour-Tory swing voters and the Ukip-Tory waverers. “With a majority of 500, you have to go for both and have a broad appeal,” says Nigel Mills, a Conservative who took his seat of Amber Valley off Labour in 2010. The difference in those voters, he adds, is not as big as one might imagine, given it is a seat where most people are concerned about low wages and public services.

In his area of Derbyshire, Mills reckons Ukip will have built on its support from last time by soaking up most of those who voted for the British National party. This still leaves a few percentage points of former Tory voters potentially to win back.

“I think as it gets nearer and people are starting to see who they want in government, Ukip support is perhaps weakening a bit that way,” he says hopefully.

Stuart Andrew, the Conservative MP for Pudsey in Yorkshire, defending a majority against Labour of 1,659, is also trying to stem the loss of some support to Ukip but is cheered by the fact that Labour appears be suffering a similar degree of threat.

“The danger areas are the people I won last time who might be attracted by Ukip, and where does that Liberal Democrat vote go … It’s a battle on all fronts if the truth be told,” he says.

Pollster YouGov has found that Ukip’s early supporters in this parliament were mostly former Tories. More recent backers are split more evenly across the parties but overall, this still leaves the Conservatives with the biggest tranche of 2010 voters to win back.

There has been a debate within Ukip between those who wanted to focus on immigration and others who wanted a broader campaign. But in the end, immigration has proved the most successful argument on the doorstep for the party’s campaigners, especially given confirmation that Cameron has failed in his promise to get net migration down to the tens of thousands.

Other policy areas are framed through this prism. When talking of the NHS, Farage bemoaned the impact of migration on healthcare. In Monday’s speech on the economy, he blamed immigration for making “most households worse off than they were five years ago or 10 years ago because of the massive, massive pressure on wages” from an influx of unskilled labour.

While the Conservatives fret about the impact of this national message in the marginals, Ukip’s most important concern is winning a handful of parliamentary seats against Conservatives in counties such as Kent, Essex, Suffolk and Lincolnshire.

Despite Farage’s claims that the party will take more than 10 seats, enabling him to potentially hold the balance of power, one senior Ukip official acknowledges the party will be happy with four seats and very happy with six.

The overwhelming priority for Ukip is Farage’s own campaign in South Thanet – his seventh attempt at entering parliament – especially given his pledge to stand down if he does not win. The Clacton seat of Tory-to-Ukip defector Douglas Carswell, Thurrock, and Castle Point in Essex are the others considered by his team to be the most likely chances of victory.

Facebook Twitter Pinterest Jamie Huntman, Ukip’s candidate for Castle Point in Essex, is talked of as a future party leader if Nigel Farage fails to win in South Thanet. Photograph: David Levene/The Guardian

Jamie Huntman, one of the few Ukip candidates with a chance of entering parliament, is now being talked up by party insiders as a potential leader if Farage fails. The timber merchant, standing in Castle Point, is convinced he is in with a strong chance by campaigning on behalf of the “left behind” voters neglected by the Tories in an area where Labour no longer has a presence. Immigration will be a major focus, he says.

“Castle Point is made up primarily of people who have migrated out of the East End of London and made their home in Essex,” he says. “People often say immigration isn’t a problem in Castle Point so why is it such a big issue here? One of the reasons is that people left their communities in the East End because there wasn’t a community left there and set up another one here. I think Essex will lead the way for Ukip in May, as it already does with Douglas Carswell in Clacton.”

Ukip’s aims have changed since the last election when its then leader Lord Pearson struck gentlemen’s agreements not to field candidates in the seats of anti-EU rightwingers. These days, the party is making an effort in every seat, with grand ambitions of coming second in hundreds across the Tory south and Labour north in preparation for a bigger breakthrough in 2020. But to have a chance of this, Ukip will need to prove it can do more than snap at the heels of the Tories by actually winning seats under a first-past-the-post system – starting with Farage in South Thanet.