The recession has led to identity crises for all the political parties. Labour cannot decide whether it stands for investment or cuts. The Conservatives revert to Thatcherite economic policies while claiming to be progressive. In a curious way the Liberal Democrats have been thrown into turmoil, too.

The curiosity arises from the obvious fact that their Treasury spokes-man, Vince Cable, is the star of the recession, a figure so popular that he can write a book on economics and turn it into a bestseller. And of course the adulation is partly deserved. The Liberal Democrats led the way on the need to nationalise Northern Rock and supported a fiscal stimulus during the recession. They have been more forthcoming in where they might cut compared with the other two bigger parties and have gone into a little more detail about their tax plans.

But this is where their problems begin. For the Liberal Democrats, even more than the bigger two parties, policies relating to "tax and spend" are about symbolism rather than reality. Nick Clegg will not be Prime Minister next year and Cable is unlikely to be Chancellor. But their policy pronouncements give them an opportunity to show the voters where they stand as a party and also to influence the wider debate.

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Over recent days the message has not been clear. Clegg began the week by pledging "savage" cuts. In doing so he risked legitimising the Tories' position even though Clegg and Cable regard David Cameron's view that public spending should be cut during the recession as crazy. By yesterday, Clegg's message had moved on to one about a new tax on homes worth a million pounds. Spending cuts and taxes on the wealthy are not necessarily contradictory and are, in some ways, complementary. Any party that wins the next election will have to cut some spending and put up taxes. But tonally the message was blurred.

In between those two pronouncements a policy detail came into view. As the Conservatives are discovering, those wretched policy details can get in the way of the joyful machismo around the issue of cuts. Many in the shadow cabinet want to launch policies that at first will cost more money. Similarly, Clegg came under pressure at the weekend to give an example of a savage cut. He highlighted the party's commitment to scrap tuition fees. At which point the former leader, Charles Kennedy, spoke for many here in Bournemouth when he intervened to insist that the pledge to scrap tuition fees should stay.

Similar tensions surfaced within seconds of Clegg floating the end of universal child benefits. "Unfair and unworkable" is the brief summary of Steve Webb's response. Webb is another senior MP who is also an economist. The Lib Dems are short on firepower but they have a lot of economists in their parliamentary party, not always an advantage for leaders seeking to float a few vaguely thought through ideas.

Their most famous economist popped up yesterday to clarify matters. Cable declared that he and Clegg supported the abolition of tuition fees, but the policy would not be a priority. Given that the Lib Dems can only win limited power in a hung parliament I would not like to be the equivalent of one of their low-priority policies. But Cable's contortion shows how they have to stretch awkwardly in order to convey their chosen message of savage economic prudence and social justice.

Perhaps the internal tensions and blurred message are the unavoidable consequence of a party taking on Labour in the north of England and the Conservatives in the south. As ever there is much talk in Bournemouth about their strategic conundrum. One senior Liberal Democrat MP described it to me as the party's paradox: it wants a hung parliament and yet its best hope is to gain seats from Labour. In gaining seats from Labour it makes the chances of an overall majority for the Conservatives more likely.

What is increasingly clear is that if there is a hung parliament, the Liberal Democrats will not join either of the other parties in a formal coalition, although some at the top would be tempted.

On Sunday David Cameron wrote an article claiming common cause with the Liberal Democrats on many issues. Once again, Cameron was copying Tony Blair. In the run-up to the 1997 election, Blair wrote an article at the start of the Liberal Democrats' conference urging their supporters to "come home" to Labour.

As with Blair, Cameron's article had nothing to do with the Liberal Democrats and everything to do with his aim to claim the centre ground, quite a challenge given his approach to public spending, tax and Europe. On all three policy areas, especially Europe, the Liberal Democrats would not work with the Conservatives in a hung parliament, as a briefly ubiquitous Kennedy made clear at the weekend.

There is not much point in the Liberal Democrats or the rest of us speculating about a hung parliament. Probably there will not be one. I suspect the reasons for the confused messages at the conference are anyway less to do with their tactical conundrum. The Liberal Democrats would go mad trying to solve tactical dilemmas because there is no solution. The real explanation for the awkward projection is more mundane. First, it is extremely difficult forming pre-election economic policies that are credible and popular in a recession. We will discover this at the Labour and Conservative conferences, too. Second, Clegg, like previous Liberal Democrat leaders, is desperate to be heard, as if being heard is an end in itself. Sometimes he shouts too loudly in order to get a headline, when he does not always have to do so.

In the end he will be heard because he occupies a distinctive space. Clegg was at his best at a fringe meeting yesterday lunchtime on the environment when he spoke with unscripted passion. The issue links many of his genuine interests, with climate change demanding action at a European level and locally.

He dismissed the Tories' "fake green rhetoric", exposed by their alliance in Europe with parties that do not believe in climate change, but also cited co-operatives in Denmark as an example of what people could achieve locally, irrespective of what is decided at a European level. On tax the Liberal Democrats are the most boldly redistributive of the parties, or at least they were when I last checked. Their tax and spend plans are subject to frequent revision, the single advantage of the lack of media attention. They can make changes without any one noticing.

There is nothing as vivid and accessible as their opposition to Iraq in their current policy agenda, but enough to be going on with. Their more complex challenge comes after the election and not before. The environmental issue explains why as it symbolises a wider theme.

At yesterday's fringe Clegg pleaded for the green forces to unite behind the Liberal Democrats. They will not do so. His party will attract support but some environmentalists will vote Green, others will opt for Labour. Some might back the Tories. The progressive forces are fractured and while they remain so the party Clegg described as the fake greens have the space to win big majorities as it did in the 1980s.

s.richards@independent.co.uk