Iain Duncan Smith will receive a public warning today from one of his own MPs that he cannot take it for granted that he will still be Conservative Party leader by the next election.
Nigel Waterson, Tory MP for Eastbourne, has hinted that the party may decide on a change of leader if next year's local council elections, in May, produce disappointing results. He is the first Tory MP to talk publicly about removing Mr Duncan Smith from the leadership.
His remarks, in a pre-recorded interview, will shatter Mr Duncan Smith's hopes of "drawing a line" under one of the worst weeks in the history of the Conservative Party.
They also demonstrate that Mr Duncan Smith's confident prediction that he will be in office for the rest of this Parliament is not universally shared by his own MPs.
Mr Waterson told BBC1's On the Record programme in an interview to be broadcast today: "I don't think that any leader can expect necessarily to stay in that role for the whole of a Parliament, if progress is not being made.
He added: "Halfway through this Parliament, which coincides to some extent with the May elections, local and other elections, would be a good time to review things."
Mr Waterson's comment runs directly counter to what the Tory leader claimed in an interview with yesterday's Daily Telegraph, when he said: "I have got until the next general election to take my party forward and win it. That's what I intend to do."
Privately, many Tory MPs will talk freely about the possibility of finding a new leader, probably in the New Year – although in the same breath they adamantly deny that there is a plot to remove him.
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