The majority suggest Labour will have most seats, but none show either party close to the 326 needed to win outright. Little wonder, then, that such attention is being given to what might happen if neither secures a majority.
With Nicola Sturgeon appealing to Ed Miliband to collaborate in order to stop the Conservatives and Nick Clegg offering to be the “Tories’ heart or Labour’s brain” in the event of a stalemate, speculation about possible deals is beginning to dominate campaign tactics.
Unable to unblock the deadlock, Conservatives are raising the spectre of a Labour Government beholden to the Scottish Nationalists – a fear reinforced at Monday’s SNP’s manifesto launch which signalled that the latter had no intention of restricting themselves to purely Scottish affairs.
Unsurprisingly, neither the Conservatives nor Labour are contemplating deals, at least publicly.
With five years’ experience of coalition government – as well as experience from the UK’s own devolved assemblies – there are clear lessons for those involved in any post-election deals.
Sometimes arrangements work well, with consensual, consistent and informed decision-making. Others are characterised by paralysis and fudge, with minor parties exercising disproportionate power.
First, there are institutional considerations. Westminster now has fixed elections so that politicians will have to find a way forward, at least in the short term. The 2011 Act requires either a vote of no confidence in the Government or a two-thirds resolution of the full House of Commons to call an early election. Neither is impossible, but there will be strong pressure to construct some kind of deal.
Second, numbers matter. Where one party is marginally short of a majority, the temptation will be to go it alone. However, any such arrangements are unlikely to survive the full term.
Mr Clegg stresses he would work with whoever formed the largest party. Even this might not be straightforward since, it is possible that the Conservatives could emerge with more votes but fewer seats.
While in 2010 the only two-way deal capable of a majority was a Conservative and Liberal Democrat one, more permutations might be possible this time.
Third, there is precedent. Views might differ about the coalition’s record, but few could deny that it has been a stable administration. Elsewhere, this tends to encourage repeat alliance patterns.
Fourth, there is the question of motivation, specifically the prize being sought. This might include ministerial posts – attractive to leaders, less so to backbenchers who have to defend such deals – but, this time, securing policy concessions might be the greater prize.
Fifth, there are internal party pressures. Although Mr Clegg argues that Liberal Democrats have moderated Conservative ambitions, rank-and-file supporters might be more concerned about tuition fees and the failure to secure a reformed electoral system.
Sixth, there is the issue of compatibility, both people and policies. Before the 2010 election, Mr Clegg argued in his pamphlet, The Liberal Moment, that they should be looking to replace Labour as the “progressive movement”. A Labour-Liberal Democrat arrangement was the more natural outcome but numbers simply did not allow this. The ability to work together is important, something that Mr Cameron and Mr Clegg were keen to convey from the outset. By contrast, Labour would find it difficult to work with the SNP in any formal coalition. The scars of last year’s referendum remain deep. For Labour, although it would not be conceded at this stage, a deal with the Liberal Democrats would be preferable.
Finally, there is the deal itself – another formal coalition or a more limited “confidence and supply” arrangement.
In 2010, Mr Clegg went for the former, no doubt recognising the risk that, as has happened, the senior partner would get most credit for successes and his own party the blame for failures.
This time, the deal that is struck, and the parties involved, could be even more complex.
Colin Mellors is Emeritus Professor of Politics at the University of York.