War gaming is already under way on the number of seats David Cameron might need to form a minority government after the election, with the critical number set at about 284-290.
By the time the final result from St Ives is declared at lunchtime on 8 May it will be clear whether Cameron is in that zone, and can start to try to form a government involving the Liberal Democrats and, in a looser arrangement, the Democratic Unionist party in Northern Ireland.
If the Conservatives secure 286 seats, the Liberal Democrats 27 and Ukip one, with the underlying support of nine DUP members, Cameron would be under no pressure to resign. Having reached the magic 324 required to secure a majority for a Queen’s speech, he can start talks with Nick Clegg; and the Lib Dem leader can do so without much complaint in principle from his party in the light of the last five years.
Ranked in the anti-Cameron bloc would be 267 Labour MPs, 47 Scottish National party MPs plus a smattering from minor parties. These would include the SDLP in Northern Ireland and Wales’s Plaid Cymru which are projected to win three seats each, plus one Green and the independent candidate Lady Hermon, a law lecturer and the widow of Sir Jack Hermon, the former chief constable of the Royal Ulster Constabulary.
Together those amount to just 322. (Outside both blocs are the abstentionist Sinn Feín and the Speaker of the House.)
The precise distribution in Scotland between the SNP and Labour does not matter for these purposes either. Both parties have committed themselves to Cameron’s removal from Downing Street.
These illustrative numbers are circulating among those involved in post-election scenario planning and show the incredible tightness of the potential margins. If the numbers edge towards Labour, Cameron will lose his majorityand Ed Miliband, the SNP and Plaid will be on TV screens urging the incumbent to quit.
But the central scenario shows the importance of the Lib Dems to the outcome.
Clegg can argue that he always said he would talk first to the party with the most seats, and in this scenario it would be the Tories. The deputy prime minister is also likely to argue that there is greater stability in a Tory-Lib Dem coalition than one involving an array of parties. He has, for instance, already ruled out working with the SNP and expressed his distaste for multi-party coalitions.
Labour, however, can point out that in 2010 Clegg did indeed speak first to the Conservatives, but was in talks with Labour within two days of the election outcome, if only to give himself some negotiating leverage with Cameron. Labour can also argue that the momentum is with Miliband’s party since the number of Tory MPs will be down and the number of Labour MPs up.
It is likely Labour will start to put pressure on the Liberal Democrats in the next fortnight over whether they are truly willing to give Cameron a referendum on Britain’s membership of the EU in return for power.
The argument likely to be mounted is whether the Lib Dems truly prefer putting the British economy through two years of political uncertainty simply because of a potential disagreement of one year over how fast the current account deficit should be brought into balance. It is also argued that the Scottish experience has disproved the theory that referendums clear the air, one of the chief arguments for an EU referendum.
Labour will be considering whether the Liberal Democrats under Clegg are detachable from the Conservatives, or whether he is too ideologically wedded to Cameron. The assumption is that Clegg will survive in his Sheffield Hallam constituency.
There is a counter-intuitive view in Labour that it might be better for the party if Clegg remains in charge after the election. First, he is disillusioned with Cameron as a person, feeling he did not provide the leadership required to defeat the rightwing element in his party. Moreover, Clegg as much as anyone believes in the principle of coalition.
If, however, Clegg was defeated, the party would also be left with no deputy leader since the post holder, Malcolm Bruce, has left parliament.
MPs would have to elect an interim leader. The most likely winner would be either Norman Lamb, a long-term ally of Clegg, or Ed Davey. Vince Cable, the social-democratic business secretary and the man most attuned to Labour, has yet to indicate he wants the job.
It is suggested that Tim Farron, popular with the party rank and file, could win the full party leadership in the autumn but probably not the interim leadership. But by then the die will have been cast.
The argument is that it would be a big call for Lamb or Davey to take the party into coalition with Labour, and the safer course might be to stick with the Tories or to leave government. Either way, much will depend on the political balance of the Liberal Democrat parliamentary party once its diminished forces return from the battlefield.
The Liberal Democrats have already appointed their negotiating team, and it may include two MPs who lose their seat: Lynne Featherstone and Danny Alexander. The other three are David Laws, the education minister; Steve Webb, the pensions minister; and Kate Parminter, a Lib Dem peer and former chief executive of the Campaign to Protect Rural England.
A further factor is how Labour behaves. In 2010 the influential voices of John Reid, David Blunkett and Alistair Darling all rejected the idea of Labour trying to form a coalition of the losers. If Miliband is serious about coalition, and it may not be necessary, he will need to have lined up similar voices to persuade the party that 2010 and 2015 are different. It would require supreme party management skills.
No Labour people are willing to discuss all this in public at present because Miliband, like Cameron, needs to keep the hope alive that he can secure an overall majority – something he was close to achieving but for the SNP’s tidal wave of popularity that has hit Labour in Scotland.
But like much else in this election, it is often what is not being discussed that is far more interesting than what is being discussed.
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