The most pernicious lie in politics is that the press is a democratising force. Journalists congratulate themselves for promoting democracy even as they seek to shut it down. Witness the frantic campaigns in the Mail, Telegraph, Sun and Express to crush Nick Clegg and the Liberal Democrats. He's no firebrand, but the rightwing press knows the Lib Dems would introduce proportional representation and a fairer party funding system. The press barons would no longer be able to push an unrepresentative party into office or easily manipulate it once it's there.

The liberal press claims to provide an antidote to these powers, but it still allows them to frame the question. It is obsessed by Westminster politics and the narrow range of issues that divide the two main parties, while neglecting both the external forces that limit political choice and the grassroots movements that seek to confront them. The true home of most political coverage is the gossip column.

The media's monopoly on debate kept the political doors locked. New technologies are blowing them open. Politics, like the media, has just gone plural. The public assault on the corrupt old powers, made possible by the internet and mobile phones, is a raw, uncertain movement. It ebbs and flows, launches new adventures then soon loses interest. This reflects the wider public mood: we don't have our forebears' patience for politics. Gone is the stubborn loyalty to parties and leaders, which guaranteed corruption and complacency. Gone too is the sustained mobilisation without which the old order can't be dislodged. The party machines that crushed initiative and bullied dissenters are crumbling. So is the sense of shared purpose required to confront wealth and power. Somehow we must build a movement that sticks around but remains exciting: a 30-year mobilisation that can survive the 30-second culture.

There is no shortage of initiatives. I have come across three campaigns, Hang 'em, Vote for a Change and Progressive Parliament, which have the same aim – to help people vote strategically for a hung parliament – and almost identical tactics. Three others – Power 2010, 38 degrees and Blank Vote – are pursuing similar reforms. For the most part they don't acknowledge each other's existence, let alone seek to join forces: how many times does this wheel have to be invented? But despite these familiar failings, they could, if they stick with it, inflict grave damage.

Hang 'em, for example, asks its followers to vote for candidates who belong to a smaller party or have a record of defying their party machines and have a realistic chance of winning. You might have to swallow hard, but if a hung parliament introduces a fair system of proportional representation, this will be the last tactical vote you'll ever have to cast.

The Liberal Democrats, who have the most to gain from a hung parliament, have boneheadedly failed to grasp this opportunity. Instead of supporting Hang 'em's proposal for a single list of Lib Dems, Greens, nationalists and independents, they're campaigning against plausible candidates from the smaller parties, even where the Lib Dems have no hope of winning. If, for instance, they urged their supporters to vote Green in Brighton Pavilion, Caroline Lucas would clean up. His failure to recognise his party's wider interests suggests that Clegg is no better than Brown and Cameron at seeing how politics has changed.

Of the other grassroots campaigns, two stand out. Power 2010 is a demonstration in two senses: a demonstration against the old politics, and a demonstration of how it could be reformed. It asked the public to make suggestions for changing politics in this country, ran a two-day public convention to pare down the ideas, and then asked people to vote for the five best policies. The voters chose a proportional voting system, scrapping ID cards, an elected second chamber, allowing only English MPs to vote on English laws and a written constitution. The democratic process Power 2010 used to create its manifesto grants it, when it lobbies candidates for these reforms, a moral authority the parties don't possess.

Even more interesting is the issue-based campaign, Give Your Vote. It makes the point that key political concerns don't stop at national borders. Life in poorer nations is often dominated by decisions made elsewhere. The UK, Give Your Vote argues, has particular influence in Afghanistan, Bangladesh and Ghana. We are fighting a war ostensibly for the good of Afghanistan but without the consent of its people. Climate change means that decisions made in the UK, the world's seventh-biggest carbon emitter, rip through Bangladesh; but Bangladeshis are not consulted. Trade liberalisation imposed on Ghana by the IMF and the World Bank has kept its people in poverty. Yet Ghana has no significant voice in these bodies: they are controlled by rich nations such as the US and UK.

Give Your Vote helps citizens in those countries to question candidates here. Having got their answers, they decide who they want to elect and text their decision (via a local number) to someone in the UK who has pledged to vote in our general election on their behalf. Afghans, Bangladeshis and Ghanaians will be casting their votes this Friday in the world's first cross-border election.

This is a small sample of tactics used by grassroots movements to promote neglected issues and change the political system here. It is the beginning of a new politics, in which party loyalties are breaking down and elections could be fought over issues, not identities. It threatens to curb the excessive powers of the press, party fixers and prime minister. Alternatively, if it remains fickle and fragmented, it will disappear on 7 May and have to be invented all over again at the next election.

There's a good chance that this election will produce a wildly unrepresentative outcome: a majority of the seats won by a party with a minority of the vote. If this happens, the new movements will face their first major test. If they are serious about confronting power, they will come together; perhaps to create a British colour revolution. I suggest ginger – its purpose would be to ginger up British politics, while the campaigns that formed it would function as ginger groups: vanguards seeking to radicalise wider constituencies. If they are not serious, they will let the moment pass; yet another puff of public anger that dissipates without result.

So I challenge the campaigns I've mentioned – and the 400 others doubtless lurking in cyberspace – to prove the cynics wrong this week by contacting each other and deciding what to do in the event of an unfair outcome, then publishing a brief joint plan for a colour revolution before the election. Then we will know that these movements mean business and can put their divisions aside. In the weeks following this election, if we channel our anger into these campaigns, we could break our rotten system. Alternatively, we could roll our eyes, grumble that politicians are all as bad as each other and, once again, turn in on ourselves. Which is it to be?

• The headline for this article was altered at the request of the author