Ahead of May's European Parliament election, with issues such as the economy and immigration to the fore, none of Britain's three main parties are stealing a march on their rivals.

The co-governing, right-of-centre Conservative Party, also known as the Tories, led by Prime Minister David Cameron, is struggling.

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Nigel Farage - in full flow in the European Parliament (Photo: European Parliament)

What remains of its traditional support base, including some MPs, often seems opposed to the modernising, socially liberal direction of its leadership.

Cameron's Tory supporters talk of "detoxifying the Tory brand.” His Tory opponents talk of abandoning the party's tradition and identity. Either way, pro-gay marriage, wary of being too hard on immigration, and broadly in favour of the EU, the party of Cameron is a far cry from that of his predecessors.

Still, the Tories are polling better than perhaps many observers expected.

They seem to have weathered the economic storm, and while a YouGov poll earlier this year put them in third place on 23 percent behind both Labour (32 percent) and the Ukip (26 percent), a recent ICM poll ICM poll put them second on 25 percent.

UK voters will elect 73 MEPs to the 751-strong EU assembly on 22 May.

The Tories' relatively low poll ratings are hardly a cause for celebration, but they are higher than those of previous governments during mid-term elections which have then gone on to secure another term.

And what of the left-of-centre Labour Party? Despite being ahead in the polls, it does not exactly convince as a political force. Its awkward, straight-out-of-school leader Ed Miliband, regularly comes behind Cameron and the current star of the show, Ukip leader Nigel Farage, in the popularity stakes.

Up until a relatively successful party-conference performance last September, there were grumblings among senior Labourites that Miliband and his leadership team were failing to set the political agenda.

This criticism, albeit one subdued by Labour's upturn in the polls, remains accurate.

The current Labour Party may be led by someone with 'Red Ed' as a moniker, and a famous socialist for a father, but on the big issues – immigration (it needs capping), on the economy (the deficit needs cutting), on welfare (it needs reform) – Labour, rather than finding its own voice, is largely singing from the same hymn sheet as the Conservative Party.

While Miliband and Cameron have their own problems, they are nothing compared to those of the Liberal Democrats and its colossally unpopular leader, Nick Clegg.

And little wonder.

With the announcement of every policy from what is effectively a Tory-led government, the Lib Dems are accused of betrayal by their erstwhile, largely anti-Tory supporters, as shown by their now infamous volte face on increasing university tuition fees.

If the recent poll ratings of less than nine per cent prove accurate, the most pro-EU of all the major parties could well end up without a single MEP.

But viewing the UK's party-political landscape solely in terms of the traditional duopoly (plus the Lib Dems) misses the big political story, and what is likely to be the major theme of the EU elections: the rise of Ukip.

Just 100 days to stop UKIP

Established in 1993, this nominally right-wing party of "fruitcakes, loonies and closet racists", as Cameron described it in 2006, has now become the party the others seem to fear the most.

This has long been the case for the Conservative Party, the body on which Ukip has long been feasting, sucking up those disaffected by Cameron's modernising leadership.

But now the Labour Party has, in the words of one senior minister, organised an "attack team" focused entirely on combating Ukip, and the Lib Dems, in the words of Clegg, announced that "we have just 100 days to stop Ukip becoming a major force".

In some ways, the political mainstream is right to be concerned: Ukip is relatively popular.

On average, current polls suggest it could gain around 25 percent of this year's vote, eight percent more than it received in the 2009 EU elections.

That means Ukip will eclipse the big story of the last EU elections: the over-hyped, far-right British National Party (BNP).

Indeed, the BNP, having polled six percent back in 2009 – a result which prompted much ostentatious hand-wringing among the main parties about right-wing extremism – has now virtually disappeared, with its leader Nick Griffin's declaration of bankruptcy last December the final confirmation, if any were needed, that it is no longer a going concern.

The absence of the far-right from the EU elections is one of the notable features of the UK political scene compared to other EU nations.

But it is perhaps a mistake to see Ukip in terms of the right, let alone the far right. Because what its emergence represents has very little to do with any of its specific, right-wing policies (this is just as well, given its leader Nigel Farage recently declared its existing manifestoes obsolete)

As the Observer's Andrew Rawnsley noted, focus groups suggest that many Ukip voters are unaware of the party's policies beyond its flagship opposition to the EU and its hard-ish line on immigration.

And even then, according to an Ipsos Mori survey of Ukip's support, the majority rate the economy, unemployment, and immigration as more important issues than Ukip's core offering: UK independence from the EU.

Protest votes

Ukip's current populist success owes far more to the weakness of the party-political mainstream, than it does to the strength of its own political ideas.

That is, the votes for Ukip are protest votes, but they're a protest against the political class as a whole, a protest against its deracinated, careerist cast, and a protest against what appears as an elite consensus, from the reluctance to discuss the 'big issues' such as immigration, to its cosmopolitanism and politically correct liberalism.

And in Farage, a man rarely without a pint in his hand and a non-PC bon mot at the ready, Ukip is led by the very antithesis of the suited, booted, and carefully spun professional politician.

Ukip's rise, then, rests on what it is not. It rests on the estrangement of vast swathes of the UK electorate from the traditional parties, an estrangement that afflicts not just old Tories, but, as one academic notes, also the core of Ukip's support, "[the] low-income ... and working-class.”

It would perhaps be a mistake to overestimate Ukip's own strength then. Far stronger, it seems, is that widespread sense of estrangement underpinning Ukip's rise.

After all, the largest electoral grouping (currently over 60 percent) in this election, or indeed any other recent UK election, consists of those who do not vote at all.