But the struggle to be taken seriously tells on Paddy Ashdown's furrowed brow, always only a dangerous snicker away from irrelevance. Walking a perilous path above the rocks of mockery, he reaches for the highest redoubt on the moral high ground in search of justification for his party's existence. That is what the Lib Dems are for.
Their manifesto is undoubtedly the best of the three. It offers those things we know we need most: proportional representation, taxation to spend on a real improvement in education, green taxes to pay for public transport, a strong, positive view of Europe and a radical trust in genuine democracy. Costed, sensible and popular goals, if only ...
Among liberals, you hear the strong wish that a dangerously large Labour landslide might be tempered by a goodly slab of Lib Dem seats, guarantors of radicalism to stop Labour slithering further into the mud of compromise on every issue. If only ...
The irony is that just as they have found a valuable ideological role, outflanking Labour on the radical wing, they appear to be in trouble. Playing piggy-in-the-middle for all those years - left of Tory, right of Labour - was a miserable squeeze. Now at last circumstances and Paddy Ashdown's boldness combine to offer a bright streak on the political spectrum. And yet, alas, the outlook may be grim.
At the weekend their poll rating fell to a dismal 9 per cent - a blip maybe, or maybe not. According to MORI, intending Lib Dem voters are the softest and least tenacious supporters of all three parties. They are good citizens, far more likely to go out and vote on the day than either Labour or Tory voters - but when asked how strongly they support their party, only 9 per cent of them are enthusiastic enough to say their support is Very Strong (while 21 per cent of Tories and 29 per cent of Labour describe their support as Very Strong.) Asked if they might still change their vote, 37 per cent of Lib Dem supporters said yes, compared with only 33 per cent of Tories and 18 per cent of Labour.
What do we know about the Lib Dem voter? You might expect a gallant band of radicals, keeping alight the flickering candle of liberal idealism through these dark ages. Not so, sadly. Lib Dem voters seem to have remarkably little in common with their leaders or their manifesto. Take Europe. Now surely Lib Dem pro-Europeanism has been loud and clear, a heart-warming clarion call in the growing Euro-sceptic mood of the times. Astonishingly, according to MORI, more Lib Dem voters want to withdraw from Europe than either Labour or Tory voters. What on earth does that mean?
What else do we know about Lib Dem voters? They are of a higher social class than Tory and Labour supporters, with more ABs and fewer DEs. A higher proportion of the readership of this newspaper votes Lib Dem than of any other paper ( 20 per cent), and in religion they are rather more non-conformist than the other two parties. On one issue they are in tune with the Lib Dem leadership: many more of them make education their priority than voters for other parties.
But how radical are they on traditional liberal issues? Not at all. Take the monarchy, for instance. Only 20 per cent of Lib Dem voters are anti- monarchist, compared with 32 per cent of Labour and 11 per cent of Tories. On caning in schools, a surprising 64 per cent of Lib Dems want it brought back. On abortion, a poll of women showed that Lib Dems were more anti- abortion than either of the other parties: 27 per cent of Lib Dem women want abortion made more difficult and only 9 per cent want it to be made easier.
Bob Worcester of MORI is caustic about the Lib Dem voter: "There is no such thing as a natural Lib Dem. It is not a calling or a commitment but an opt-out, or else a tactical vote. People float in and out of this way station. If you are angry with your natural party, you turn to the Lib Dems. It is the dustbin vote."
This is depressing. Ashdown and his team with their fine manifesto step out feebly supported by little more than a bog of random reject votes. But there are, as I have said, a great many very good reasons to support the Lib Dems, so perhaps it does not matter that their vote comes from those who do not much agree with them.
Despite his harsh words, Bob Worcester has a little comfort for the Lib Dems. He thinks they will do better than their present poll showing. The prospect of a 200-seat Labour landslide will frighten some of the more hesitant would-be Labour voters into stepping back in alarm and voting Lib Dem instead, to restore some balance. Tactical voting in the south is on the increase, with some 11 per cent of voters saying they will vote tactically to get the Conservatives out. Lib Dem success in local government should help, though converting local to national votes has always been an uphill struggle and a constant source of bitter disappointment.
This is a sad story. It is by no means clear that Labour will deliver proportional representation unless forced to by the Lib Dems - only Blair knows his true intentions. Who will stop Labour sliding further into anti- Europeanism? Who will keep Labour at least a little green? Who will dare to tell Labour that taxes may have to rise, or protect us from some of Labour's more illiberal instincts?
If yet again the Lib Dems find themselves a small and haphazard little clump on the green benches, what then? Ahead may lie just more of the same, a lifetime of permanent protest, waving and drowning from the sidelines for ever.
Politics is the most wasteful of all endeavours. If Lib Dem candidates and local parties put a fraction of their energies into a single issue campaign or into volunteering for some good cause, they could achieve almost anything with the time they waste on national political activity. Consider the leaflets printed, the myriad committee meetings, canvassing, fundraising, Christmas fayres and summer fetes, petitions and door knocking. Think of the emotional energy spent on frictions and rivalries, plotting for places on policy sub-committees all too soon forgotten. What an empty waste of weekends and evenings, doing so little good to anyone. What keeps them going? Paddy Ashdown grits his teeth and juts his jaw with an air of noble endurance. Almost unerringly he says and does the right thing - and so, maybe, one day, perhaps, if only, if only ...