Leading article: This historic opportunity must not be missed

This election campaign has felt almost like a liberation. The prison walls – the stultifying, spirit-crushing assumptions of the long era of two-party politics – have crumbled. The surge in support for the Liberal Democrats has unlocked something precious: a feeling among the public that, for the first time in a generation, a radical overhaul of our political settlement could be possible.

That feeling – combined with the enduring uncertainty over the result of the election – is a tonic for our democracy. The public sense that their vote matters. When one considers that this campaign began against a backdrop of rampant cynicism and apathy, stirred up by MPs' abuse of their expenses, this transformation looks all the more remarkable. And welcome.

But while this is a moment of hope and freedom, it is also a moment of danger for the popular movement for change that has been set free in recent weeks. Nick Clegg's party has made an astonishing breakthrough. But though the mould of British politics is fractured, it is not yet broken. And the vested interest of the "old politics" could still preserve it. Despite the drama of recent weeks, there remains a considerable risk that Britain could wake up on Friday morning to discover we are in for four or five more years of "business as usual" politics under a Conservative government.

The Independent is proud to be closely associated with the political mood which has gripped large parts of the nation in recent weeks. We have campaigned for reform of the voting system since the 2005 election, when Labour won a double-digit majority with little more than a third of the popular vote. We gave a fair wind and ample coverage to the Liberal Democrats long before it became fashionable or expedient to do so. We have also consistently argued, in defiance of the scaremongering of powerful opponents, that a hung parliament is not something that Britain should fear; that cross-party consensus politics is not the opposite of strong, intelligent government.

The Conservatives have been the loudest of those scaremongers. The party talks of the need for change in Britain and its leader, David Cameron, likes to emphasise the manner in which the party has renewed itself. And it is true that the Conservatives are no longer the reactionary rabble that fought the 2005 election. Their focus on improving the state education system and the National Health Service does them credit. So does their plan to encourage the voluntary sector to play a greater role in delivering public services. But in a host of other areas – from criminal justice, to their hostility to the European Union, to their attitude to immigration – the shift has been superficial at best.

Worse, the Conservatives have set their face resolutely against the fundamental change that would breathe new life into our body politic: electoral reform. If the Conservatives win the highest number of seats this week – an outcome that the opinion polls suggest is increasingly possible – they would be a formidable roadblock to the overhaul of the voting system that the public want and deserve. The lid could yet be slammed firmly down on all those hopes for a new way of doing politics.

Let us be clear. We do not argue that Labour deserves public support on the basis of its record in power. Gordon Brown is due immense credit for the manner in which he handled the 2008 financial crisis. And Labour can point to some worthy and lasting achievements, from political accord in Northern Ireland, to the introductions of civil partnerships and the minimum wage. But the blind support for the disastrous US-led invasion of Iraq in 2003 and the dishonest way in which the case for that intervention was made drained the party of moral authority. And while Labour's efforts to reform our public services and cut our national carbon emissions have been a disappointment, its record on civil liberties has been a disgrace. This feels like an exhausted administration.

We also recognise that Labour's decision to pick up the banner of electoral reform has all the moral conviction of a sinner recanting on his deathbed. And the electoral reform it has floated – the alternative vote – is a non-proportional sham. And yet Labour's position on this key matter, its commitment to hold a referendum on moving to a new voting system, is a thousand times better than the Conservatives' flat rejection of the case for any change. For this reason alone, Labour, not the Conservative Party, would make a better coalition partner for the Liberal Democrats in the event of a hung parliament.

Electoral reform is a valuable end in itself. A party's representation in Parliament should represent its level of support in the country. The way to convince the public that their vote truly counts is to make it a reality. There is also reason to believe that electoral reform would open the door to a new era of self-confident, progressive politics in a range of areas – from Europe, to the economy, to wider constitutional reform. That is why this newspaper suggests that, if voters do not want this inspiring movement for radical political change to fizzle out once this election campaign is over, they should mark their ballot tomorrow with a larger picture in mind than simply the merits of the respective parties.

The Liberal Democrats are certainly not without their faults. But they are longstanding and convincing champions of civil liberties, sound economics, international co-operation on the great global challenges and, of course, fundamental electoral reform. These are all principles that this newspaper has long held dear. That is why we argue that there is a strong case for progressively minded voters to lend their support to the Liberal Democrats wherever there is a clear opportunity for that party to win.

Yet in those constituencies where there is likely to be a close fight between Labour and the Conservatives, there is an equally strong case for voters to cast their ballot to keep out a Tory party which incarnates this discredited "business as usual" approach to politics.

A great prize could await Britain this week: a change that could reinvigorate and re-legitimise our politics in the same manner as the great Reform Acts of previous centuries. It is that prize, above all, that we would urge all our readers to keep at the forefront of their minds when they go to the polls tomorrow. It is time to use our rotten voting system (for what we fervently hope will be the last occasion) to change the system – and deliver a new politics.