The February polls produce a pair of evenly balanced predictions for the Labour Party: either it takes control of government with an absolute parliamentary majority or it takes control of a minority government with the support of one or more third parties. Either outcome would end the string of four straight election victories for the Conservatives. They have less than a one in ten chance of winning a fifth straight victory and Boris Johnson is now odds on to lose his seat in Uxbridge and South Ruislip.
The central prediction of Electoral Calculus is that Labour will be 15 seats short of an absolute majority. Within the overall set of possible outcomes, 46 percent predict a majority Labour government and 38 percent Labour taking control of Downing Street depending on support from one, two or three "third" parties, even if the Conservatives are the largest party.
Labour would prefer to head a minority government supported by the Liberal Democrats. Liberal Democrat policies tend to be more congenial to Starmer's centre-left views than those of Labour MPs still supporting the hard-left views of Jeremy Corbyn. And Starmer could use the need for Liberal Democrat support to reject demands for hard left policies. The Liberal Democrats' big demand, proportional representation, would be rejected if put to a free vote in the House of Commons. The political attractiveness of a Labour government supported by the Liberal Democrats is not matched by its attractiveness to the electorate. There is only a 9 percent possibility of the Liberal Democrats holding the balance of a power in the next House of Commons.
In arithmetical terms, there is a 23 percent probability of a Labour minority government relying on a pact with the Scottish National party. SNP support would be conditional on a Labour government authorising a referendum on Scottish independence. While Labour is in principle against another Scottish referendum, since Harold Wilson and Tony Blair each backed referendums on Scottish home rule as the price of holding office, there is ample precedent for Starmer to endorse yet another Scottish ballot.
The least likely way for Labour to gain office, a 6 percent possibility, is by what the Germans call a stop-light coalition of MPs: red for Labour, yellow for Liberal Democrats, and the SNP's black bunny-ears logo replacing green for go. The coalition would only need to stick together on votes of confidence in the government. Labour could carry forward policies on which there was multi-party agreement and refrain from acting on issues that lack a broad consensus.
There is also a 6 percent chance of four-party No Trump coalition in which Plaid Cymru MPs had to be added to form an absolute House of Commons majority. The Labour Party would hold the Ace, as the only party that could become prime minister for what the job would be worth.
Richard Rose is Britain's senior psephologist and an expert on party government. His new book 'How Sick is British Democracy?: a Clinical Analysis' is published by Palgrave.