What does the future hold for Nick Clegg, David Cameron and Ed Miliband come 8 May 2015? Photograph: Barcroft Media/EPA/Guardian composite

The Fixed-term Parliaments Act became law in September 2011. For the first time in Britain’s history, the date of the next general election became universal knowledge. Barring either the House of Commons passing a no-confidence vote in the government (and given the coalition’s majority, this would require the government in effect to admit: “You know what? We have been a bit rubbish”) or for two-thirds of all MPs to demand an early election (about as likely as them asking for their expenses to be re-audited, just in case they had over-claimed) then the next election will be held on 7 May 2015.

Under the previous rules, the government was free to call a general election at any time during the course of a five-year parliament. In practice, the only governments that delayed calling an election until they were statutorily obliged to do so were those who knew they were dead ducks and were just hanging on for a miracle – a spontaneous eruption of billions of tonnes of oil in the Thames estuary would be handy – and to get the most out of the ministerial limos.

Almost any result is possible in May 2015. The Tories have closed the gap on Labour a little – as much due to Ed Miliband’s parody of a conference speech as the conviction of the Conservative message – while the Liberal Democrats are still bumping along on 7%, but no party has landed a killer blow on the others. Add in the Ukip factor, and the old hegemony of two-party politics looks as if it is well and truly over. At least for the foreseeable future.

It still seems likely that Labour will win the most seats – as much due to the fortunes of electoral geography as to the coherence of its message – but nothing can be taken for granted. The extent to which Ukip has made inroads into Labour’s traditional white working-class vote in the north of England, and how permanent those inroads will be, is still unquantifiable.

As is the Scottish Labour vote. Many Labour supporters in Scotland were in favour of independence, are still angry that the party campaigned so strongly in favour of maintaining the union and might vote SNP next time. The irony that Labour might have fought so hard to keep the union and its 40 MPs only to lose them anyway is inescapable.

Even if Labour does get the most seats, it is unlikely to have enough to form a majority government. This will mean it either has to form a coalition or go it alone as a minority government. It won’t be a straightforward choice. The most obvious party with which Labour might form a coalition is the Lib Dems, as they are ideologically closer than any of the other parties. There are several problems with this. First is that the Labour and Lib Dem leaderships dislike one another intensely; finding a negotiating team that can remain civil and find common ground might be tough. Labour also might play hardball and demand Nick Clegg’s removal as party leader as a blood sacrifice to satisfy its grassroots supporters, who hate the Lib Dems. Just how much of a sticking point this will be for the Lib Dems is unknown; more of one for Clegg than for Danny Alexander or Tim Farron, you would imagine.

The trouble doesn’t end there. The maths of the constituency boundaries mean that Labour will probably poll a smaller percentage of the overall vote than the Conservatives, with the Lib Dems winning a smaller number of overall votes than Ukip, despite winning many more seats.

This will, in effect, mean that the second and fourth most popular parties in the country will be forming the government; it would be unprecedented in British political history and there is every likelihood it would be considered undemocratic by many sections of the population. Even with the support of the Lib Dems, there is no certainty that Labour will be able to form a majority coalition anyway, as the Lib Dem campaign team’s most optimistic prediction is that it will win 32 seats. As a deal with either the Conservatives or Ukip is unthinkable and – given the Westminster clamour of “English votes for English laws” following the Scottish referendum – one with the SNP unpalatable, the most practical outcome of a Labour victory is that it will go it alone.

Minority government has the attraction of allowing Labour not to have to make compromises with parties it doesn’t like; nor would it be forced into making promises it can’t keep. But it is still a minefield. Every new law it tries to initiate will be at risk of defeat; every detail will become a matter of negotiation and the process could grind to a halt, resulting in legislation that satisfies no one. A public already sceptical about the ability of Westminster politicians to tackle the country’s problems would become more so, and Labour, as the governing party, would get most of the blame. After a year of this, it would be relatively simple for the opposition parties to block Labour at every turn and force a vote of no confidence. At the subsequent general election, Labour would inevitably lose seats.

Nigel Farage’s Ukip could win 10 seats in 2015, but will they be able to build their influence on such a small number? Photograph: Rob Stothard/Getty Images

The Conservatives would be in no more comfortable a position if they win the most seats but fail to secure an overall majority. If Ukip win around 10 seats, they will be too small a party for the Conservatives to contain and neutralise within a coalition, as they will still not have enough MPs to form a majority, which means that the Lib Dems will once again be their most likely partner. This will have the advantage of familiarity if not harmony, as the Lib Dems will be caught between a rock and a hard place.

Without a coalition, the Lib Dems will be condemned to political irrelevance for a generation and yet, at a time when its bargaining position and influence is at its weakest with its number of MPs substantially reduced, it will be under pressure from its grassroots not to negotiate away its principles as it did five years earlier. This will be just as problematic for the Conservatives as for the Lib Dems. With the Lib Dems committed Europhiles and the Tories desperate to avoid losing any more MPs to Ukip, the fault lines in any coalition are all too predictable. Finding a common ground to keep everyone happy will be almost impossible, and this time round the Lib Dems will be much more likely to walk away from a coalition mid-parliament rather than hang on and watch their support erode still further as they did last time.

Any coalition the Tories do form will be inherently less stable than the one of five years ago. Nor will the public be so tolerant of it. The novelty of coalition will have worn off; voters will remember how the Tories and Lib Dems were at each other’s throats in the election campaign and be wary of any reconciliation that appears to be too conveniently contrived. There is a thin line between political pragmatism and doing anything to grab a share of power, and the electorate is getting much more savvy to it. For all these reasons, the Conservatives’ best option might, like Labour’s, be to form a minority government. Yet that would come with just the same risks.

There are no easy answers and, in private, some MPs on both sides are presumably thinking that the 2015 election might be a good one to lose. Let the other side take the inevitable hits and then capitalise on their unpopularity to win an overall majority in 2020. The only two politicians definitely not thinking that way are David Cameron and Ed Miliband, because their jobs depend on the outcome. Only the one who becomes prime minister will be certain to be still in his job at the next party conference in September 2015; even then, the winner might be buying himself only an extra couple of years.

The closer the election gets, the greater becomes the sense of indecision and paralysis within the main political parties. The opinion polls offer little help or comfort. Within a week of the party conferences ending, one gave Labour a seven-point lead over the Conservatives, another put them both neck and neck, Plus Size Prom Dresses and a third indicated that Ukip had the support of 25% of the electorate and is on course to win up to 100 seats in May 2015 – mainly at the expense of the Tories in the south of the UK. It seems barely credible, but an increasing number of sitting Tory MPs have begun to wonder if their best chance of re-election is to defect to Ukip. The party leaders seem to have little idea how to calm the nerves of their supporters or what message to give the electorate to head off the Ukip threat. What could be going through their minds?

Cameron: Vote Ukip, get Labour.

Miliband: Vote Ukip, get the Tories.

Farage: Don’t vote Conservative, Plus Size Prom Dresses don’t vote Labour.

Clegg: Vote Lib Dem, get anyone else.

Cameron: We need to make our message clearer.

Miliband: So do we.

Cameron: What’s yours?

Miliband: That we can actually be quite tough on immigration.

Cameron: How odd. That’s ours too. We’re also looking at turning the clocks back to 1940.

Miliband: That’s not a bad idea.

Farage: You’re still getting it all wrong, chaps. The idea is to have no real message at all. I’ve reversed my policies on the NHS several times and no one either cares or notices. I’ve no chance of coming up with anything on which disaffected Tories and Labour voters will agree in the long term other than that they dislike things the way they are. All that matters is that I look like an ordinary bloke who drinks in pubs and that I’m not you. You need to be more like me.

Cameron: Vote Ukip.

Miliband: Vote Ukip.

Farage: Vote Ukip.

Clegg: Vote Lib Dem.

Everyone: Don’t be silly.

For the British public, though, these are both the most uncertain and fascinating of times. Will two-party politics be finished for good, or will the old order eventually reassert itself? Will Ukip prove to be a shooting star that burned out, or will it become a permanent part of the political landscape? Will three-party politics become four-party politics? Will Britain remain in the EU? Will Scotland force another independence referendum within a matter of years? What about Wales, Northern Ireland and the large British cities? What powers will they have? The answers to all these questions will ultimately lie with the public and all the signs are that many people still haven’t made up their minds about what they want. Over the next few months the politicians of all parties will be out selling their ideas and making promises they don’t know if they could keep. Who to believe? The choice is yours. Use it.

Who will sit where in the House of Commons after 7 May 2015? Photograph: Empics/PA May 2015: the post-election options

Labour are the largest party, no overall majority

Form minority government

No obligation to deal with other parties.

A quick vote of no confidence and out of office within a year.

The Conservatives, for whom this might be the best hope of getting back in power with an overall majority. Any Labour MP who wants Ed Miliband’s job.

Form a coalition

Get to stay in power for five years.

Who with?

With Labour facing a meltdown in Scotland, Labour might be stuck with doing a deal with the SNP. If Alex Salmond stands (as he has hinted he might) as a candidate, he could end up sitting alongside Ed Miliband as deputy prime minister. The Tories would choke on that.

The Lib Dems could also find themselves back in government – albeit in much reduced numbers – claiming that they always had been more of a centre-left party. Nick Clegg would have to be sacrificed as party leader to prove their sincerity.

Both possibilities are a match made in hell.

The Conservatives are the largest party, no overall majority

Form minority government

No obligation to deal with other parties.

A quick vote of no confidence and out of office within a year.

Labour, for whom this might be the best hope of getting back in power with an overall majority. Any Conservative MP who wants David Cameron’s job.

Form a coalition

Get to stay in power for five years.

Who with?

The Lib Dems have shown they are willing punchbags and would accept five more years of punishment in preference to political oblivion. They would, though, have even less influence than five years ago as they will have far fewer MPs and even less goodwill.

No one knows quite how many MPs Ukip will have – anywhere between 10 and 25 is a possibility – but they will have to be represented in any coalition to prevent any more Tory MPs defecting. Nigel Farage will then get a key cabinet role and sit next to Cameron at PMQs. A sketch-writer’s dream, but the country’s nightmare.

Will David Cameron survive after the election? Photograph: Murdo MacLeod for the Guardian The knives are out: key rivalries in the parties

Conservatives: Cameron’s job is hanging by a thread. He is desperately trying to reinvent himself as a posher Farage to prevent more defections to Ukip, and if he doesn’t win the election he will be gone. Many Tories still blame him for not winning an outright majority in 2010 and forcing the Tories into a coalition. Theresa May and George Osborne are favourites to replace him.

Labour: Many Labour MPs would be secretly relieved if their party lost the next election. The two Eds – Miliband and Balls – are felt to be a losing team that could put Labour out of office for more than a decade if given a chance at government. But they know they are rather stuck with them because it is too late to do anything about it.

Lib Dems: It’s dog eat dog. The Lib Dems have long since given up on any party unity and every MP is now fighting for survival in their own constituencies. Hence this week’s resignations of Norman Baker and Jenny Willott. What’s left of the party will reassess their allegiances after next May’s wreckage.

Ukip: The party has just one MP at present – Douglas Carswell. And he hates himself. Quite how Ukip will operate, if and when it gets more MPs, is anyone’s guess. Farage hates sharing the limelight with anyone and many potential Ukip candidates have nothing in common with one another except their dislike of Europe. JC