She has warned colleagues there is "something of the night" about Mr Howard's personality. It will increase the impression of a ruthless streak in him following the disclosures that he tried to stop William Hague, former secretary of state for Wales, running against him, in a champagne deal which broke down.
Ms Widdecombe, a doubty Tory who is taken seriously by colleagues, privately describes Mr Howard as "dangerous stuff", according to friends, who said she was determined to stop Mr Howard becoming leader of the party by detailing her objections to him in a letter to John Major, as the party's caretaker leader.
Ms Widdecombe is a supporter of a rightwing rival, Peter Lilley. She was urged by Mr Lilley's team not to carry out her threat because they feared it would rebound on Mr Lilley.
"This has been a long time coming. Basically she hates him and they didn't have a harmonious relationship at the Home Office. She was determined to set out his disadvantages as she sees it. She says he misled the Commons. That is what she feels precisely occurred. When I heard about this I was quite concerned. Those who support Peter did urge her not do do so, but she has written this letter despite being for Peter Lilley, not because of it," one of Mr Lilley's friends said.
Ms Widdecombe said last night: "I have no comment at this time."
Mr Howard admitted he fell out with Ms Widdecombe over the sacking of Mr Lewis but said it had been fully scrutinised by Parliament. "Ann and I disagreed about a very important decision, the dismissal of Derek Lewis as head of the Prison Service," he said. "I had to overrule her because there was an independent report which made very serious criticisms of the Prison Service management from top to bottom.
"Ann felt very strongly about that. We disagreed. I am convinced the decision we made was the right one and few decisions have been subject to more parliamentary scrutiny, including a debate on the floor of the House of Commons, than that one," Mr Howard said on BBC1's Breakfast with Frost programme yesterday.
Mr Hague's bandwagon gathered momentum in the country, with increasing demands for more say for the grassroots of the party in the choice of a leader. His supporters believe the 164 Tory MPs who must select the new leader will be expected to reflect the wishes of their constituency parties.
Mr Hague will be stepping up his campaign by visiting Scotland and Wales, in addition to other tours of the country. Mr Howard sought to steal the initiative by calling for a referendum on the outcome of the Inter-governmental conference in Amsterdam next June, but Mr Hague matched his call.
Lord Tebbit, a leading Euro-sceptic, came out in support of John Redwood in the Sunday Times newspaper, because "He was not on the bridge when the captain of the ship rammed it on to the rocks."
Kenneth Clarke last week tried to persuade Stephen Dorrell to drop out of the race in return for the promise of a senior position in his shadow cabinet if Mr Clarke won, as disclosed in The Independent. The former chancellor said the role of deputy leader would go a Euro- sceptic from the right. Their private meeting ended with Mr Dorrell offering Mr Clarke the chance to be his number two, an offer Mr Clarke laughed off.
Mr Clarke is still expected to lead the field on the first ballot, but will fall by the wayside in later rounds. His supporters' votes are likely to switch to Mr Hague, 36, who is staking his campaign on a pledge for a "fresh start". If Mr Hague wins, he could make Mr Howard his shadow chancellor to give the Opposition more bite against the Chancellor Gordon Brown's first Budget.Reuse content