The alternative, a snap election on 20 March, was being ruled out because it would smack of panic, and the voters would regard it as a piece of political chicanery to avoid the embarrassment of this month's Wirral South by-election.
But the decision will become clear, either way, by next Wednesday, when the Prime Minister would have to announce his intention to call a March poll. That would be the last moment at which he could avert the anticipated defeat in Wirral South, and give ministers just two days in which to salvage the bare minimum of their legislative programme.
A March election would require the dissolution of Parliament the following Monday, 24 February - three days before the by-election.
But Labour agreement would be required for any legislation that was going to be rushed on to the statute book before dissolution took place. Mr Major's senior advisers do not favour the appearance of panic entailed in that option.
Ruling out 20 March will switch feverish Westminster speculation to the next favoured bet, 10 April. However, it emerged yesterday that the April option would not eliminate the Wirral South by- election - one of the prime reasons for calling an early general election in the first place.
According to election law, the April election would require dissolution of Parliament on 12 March. The result of the Wirral South by-election will be declared in good time for the new MP to take his seat in the Commons on Monday 3 March.
Some ministers and MPs have argued that if Mr Major announced his intention to call an April election on 24 February - three days before the by-election - that would be enough to get the by-election called off.
But that decision would be in the hands of Phil Manson, Wirral South's acting returning officer, and all the indications yesterday were that Mr Manson would feel legally obliged to continue with the by-election.
If Mr Major cannot be certain of getting the by-election called off, colleagues said yesterday, he would be better off soldiering on until 1 May. "Things cannot get worse," one senior colleague said yesterday - although other Conservative MPs were not so optimistic.
A Labour victory in the by-election would again drive the Government into a parliamentary minority - opening the way for a no-confidence vote. While a defeat for the Government would precipitate a general election, there would be little point in the exercise if Mr Major made an announcement of his firm intention to hold the election on 1 May, with dissolution of Parliament on 8 April.Reuse content