At the beginning of the campaign a vote for Clegg was disparaged as a vote for Labour; then it was condemned as a vote for the Tories; now it's returned to being a vote for Labour again. One way or another the Lib-Dems are going to be condemned for infidelity after the election, which is why it is essential they remain true to their beliefs during and after the campaign.

What is worrying is the chill that has descended on civil liberties, as though freedom was some minority issue for eccentrics, rather than the oxygen of democracy. The failure of the Conservatives and the Liberal Democrats to raise the attack on liberties by the Labour party and so signal its vital importance to the electorate is one of the more depressing aspects of the last few weeks.

Thinking about my single non-transferable vote has become much harder as a result. Labour is obviously beyond the pale. The party has created a country where half a million people come under some kind of official surveillance every year; where emergency terror laws have become part of the normal policing arsenal; and where jury trial is under attack, total surveillance of communications and movement is proposed and secret courts meet to decide house arrest, without subjects ever being told what the evidence against them is.

This is not some Orwellian fantasy but the astonishing truth about Britain today, which, by the way, has foreigners open-mouthed with disbelief. What is the most disturbing aspect is this sense that civil liberties are, if not exactly taboo, a kind of special interest that broadcasters and some of the grander commentators ignore as if to delineate the political establishment's agenda by proxy.

The fear in the event of a hung parliament must be that when the grownups close the doors and do a deal away from the children, all that has happened under Labour in the last 13 years will be forgotten and we will be left with the ID card, 28 days of detention without charge, the database state and all the rest of it.

The Liberal Democrat manifesto is pretty good on liberties, but what I don't hear is Nick Clegg or Vince Cable speaking about them with the passion that is inspired by an urgent and historic mission. With the whole campaign resting on these two men's shoulders, but mostly Clegg's, it is perhaps understandable that stuff gets left out and they lose sight of one or two important themes. But that doesn't stop me waking in the morning with the fear that Labour might just survive, with the Lib Dems under one of the Milibands or the authoritarian home secretary, Alan Johnson, and be permitted to continue its campaign against liberty simply because the Lib Dems are focusing exclusively on the matter of proportional representation.

Reform of the electoral system is obviously urgent – one Ciffer pointed out in response to Edward McMillan-Scott's article yesterday that if you use the excellent BBC seat calculator and give each of the main parties and a group of minor parties 25% of the vote, Labour ends up with three times as many seats as the Lib Dems and a third more than the Tories (the figures are: Labour 315,Tory 206 Lib Dems 100, others 29).

But we should not be lulled by the vague sense that proportional representation will guarantee liberty any better than the first-past-the-post system has. It won't. What will restore liberty is political leadership and publicly articulated conditions in front of the electorate before negotiations take place. Otherwise voters who know this issue is paramount may seek refuge in a party that may well gain the largest number of seats and is at least committed to certain key reforms on the database state, albeit out of economic expediency rather than heartfelt principle.

The possibility of change is enthralling, but only if politicians are better able to guarantee liberty, control the state and roll back what Labour has done. Clegg needs to express this clearly during the next week.

• Download a postcard-sized list of 10 questions and quiz prospective MPs to establish their commitment to civil liberties here

• More Guardian election comment from Cif at the polls