The speed of Sir Michael's departure, before newspaper reports of a homosexual relationship could surface, increased the pressure to quit on three Tory MPs under a cloud of sexual or financial scandal.
But Conservative hopes that one of them, Beckenham MP Piers Merchant, accused of an affair with a 17-year-old nightclub hostess, would stand down at the general election were dashed last night. In an act of defiance, his constituency party, meeting in secret, formally endorsed him as their candidate.
Sir Michael's resignation was another disaster for the Prime Minister, whose election campaign has been derailed by allegations of sleaze surrounding his party. He is the third Tory politician to announce his resignation in a week, with Conservative attempts to highlight other election issues being drowned out.
Last Tuesday Sir Michael refused to rule out the possibility that he would stand at the election for the Eastwood constituency, itself vacated by the resignation of the ex-minister Allan Stewart. Mr Stewart himself quit after admitting an extra-marital affair.
On Thursday, Sir Michael pulled himself out of the running for Eastwood, the Tories' safest Scottish seat. He warned the Prime Minister on the following day of his intention to resign his party chairmanship.
In his letter to Mr Major, Sir Michael, a former MP who has been chairman of the Scottish Conservative Party for four years, wrote that "as a result of past indiscretion in my private life, I feel that my position as chairman of the Scottish party could become untenable". He added: "I consider that only by taking immediate action to resign can I hope to minimise the danger to my family and to the party."
Mr Major, celebrating his 54th birthday yesterday, said he supported a decision "made so speedily and in such a courageous and honourable manner". That was seen as a statement deliberately designed to put pressure on the three MPs who have so far refused to stand down though they are facing constituency pressure to do so. But it was snubbed by Mr Merchant's association which endorsed him by 43 votes to three. The local vice-chairman, Rod Reed, said: "This, in my view, is a defining moment for democratic grass roots feeling".
Labour has concentrated on highlighting the cases of MPs accused of financial "sleaze" which the party sees as a more legitimate target for attack than politicians' private lives.
Last week, Tim Smith, the MP for Beaconsfield and one of the ministers at the centre of the cash-for-questions scandal, announced that he would not fight the election. Three other MPs, Neil Hamilton, Michael Brown and Sir Andrew Bowden, remain under pressure, both having admitted that they accepted cash from a lobbyist which they did not declare.
Yesterday, the Labour candidate in Mr Hamilton's Tatton constituency in Cheshire said he was willing to stand down in favour of an anti-corruption candidate. That move increased the pressure on Mr Hamilton, although the Liberal Democrats have so far failed to commit themselves to following suit - a move which would present a real threat to Mr Hamilton's 22,365 majority. The Hamiltons were battening down the hatches last night at their home in Nether Alderley, near Knutsford.
An angry Mrs Christine Hamilton greeted news of Sir Michael's resignation and Labour's plans to stand down for an "anti-corruption" candidate with the same response: "Why should there be a statement? Nothing has changed. We're just trying to get on with Easter."
Mrs Hamilton emphasised that her husband retained the support of his constituency party and was under "no pressure at all" from Central Office to tender his resignation.Reuse content