Sack me and we'll lose the election, says IDS

The Tory leader will say to the party’s annual conference in Blackpool that he has produced both the policies and hard election results which prove he is fit to defeat Labour.

However, the eve of his speech was marred by a bizarre comment when Mr Duncan Smith suggested that he wanted to shoot the Prime Minister.

It is understood that during an interview with a television reporter, the Tory leader said: "The only real shooting I want to do in the next year and a half is shooting Tony Blair."

The gaffe is likely to encourage Mr Duncan Smith’s detractors in the party who have warned that he effectively has 24 hours to save his job - and if his speech today fails to impress, a formal leadership challenge will soon follow.

In the only scheduled event at the conference today, Mr Duncan Smith is expected to launch a new "angry" style, where he will defiantly claim to have overseen the most radical policy agenda of any party aspiring to government since 1979.

After the "patient passport" proposals for the NHS and a plan to restore the link between pensions and earnings, he will say he has honoured his promise to draw up fresh legislation, completing the first part of his mission.

And he will add that his leadership has already been vindicated by the English local government elections last May, making the Tories "the largest and fastest-growing party in local government".

His conclusion will be that there is no real choice but his leadership: "I say to everybody here today: you either want my mission - or you want Tony Blair. There is no third way."

The "third way" will be a reference to any other potential Conservative Party leader.

He will attempt a clean break from his much-derided speech last year, when he tried to make a virtue of his perceived lack of charisma, saying: "Never underestimate the determination of a quiet man."

In television interviews last night, Mr Duncan Smith gave a taste of the language he will be adopting. "Angry? Damn right I’m angry. If you think this is angry, watch the next 18 months because I have had enough of it," he said.

He added that his speech today will not disappoint. "By tomorrow, when I finish speaking, they will say, ‘At last, we are on our way to victory’," he said. "There is a plot - the plot to get rid of Tony Blair, and I am at the head of that plot."

The Blackpool conference remained charged with speculation that a core of MPs, now understood to be 15, have written to Sir Michael Spicer, the MP who decides on a leadership challenge. He needs 25 names to start proceedings.

David Davis, one of the favourites should such a race break out, played this down yesterday: "There is a procedure if people want to use it. There is no sign of it being used. There is no sign of any appetite for this."

Jonathan Steel, a member of the Beaconsfield Conservative Association, said a leadership battle would ensue if the Tory leader failed to capture the entire imagination, trust and confidence of his audience.

"His speech tomorrow is going to be absolutely crucial to what happens in the leadership next," Mr Steel said. "I have to say that if it is not a barnstormer, at least 25 MPs will be writing those letters, and then the future is going to be according to procedure for a new leader."

Mr Duncan Smith did not appear in his party’s television broadcast screened last night. Instead, Tory chiefs opted to take a viewer’s perspective - coupled with a voice-over attacking the Prime Minister.

Some reports suggest Tory plotters will meet next week to agree a course of action.