CONSERVATIVE leader Iain Duncan Smith was warned last night he was in danger of provoking a challenge to his leadership of the Tory Party after his aides launched a series of vitriolic attacks on Michael Portillo.

CONSERVATIVE leader Iain Duncan Smith was warned last night he was in danger of provoking a challenge to his leadership of the Tory Party after his aides launched a series of vitriolic attacks on Michael Portillo.

Conservative backbenchers critical of Mr Duncan Smith were talking openly of a leadership challenge "sooner rather than later" as the crisis engulfing the Conservative Party threatened to degenerate into all-out civil war.

Allies of Mr Portillo were stung by a series of comments from unnamed supporters of Mr Duncan Smith, who described the former shadow chancellor as "insane", "a cancer" and "self-indulgent to the point of madness".

Mr Portillo incurred the fury of the leadership with an outspoken attack on Mr Duncan Smith, accusing him of surrounding himself with "yes men" and provoking a crisis by sacking the party's "modernising" chief executive, Mark MacGregor.

John Bercow, who resigned from the Shadow Cabinet over Mr Duncan Smith's opposition to gay adoptions, said it was "inappropriate and unacceptable" for the leader's aides to use such language about a fellow Conservative.

He warned there was now a real prospect of a leadership challenge and added: "It is certainly possible. I think it could happen sooner rather than later. There is clearly grave disquiet."

The bitter row followed a warning sounded by Tim Yeo, the MP for South Suffolk and shadow trade and industry secretary, that his position would be under threat unless the Tories were able to pick up seats in the May council elections.

Mr Yeo said: "Certainly Michael is right that we have had a poor week and that there are divisions in the party. The verdict on all this and on Iain's leadership will be on May 1 when we have got elections to councils all over Britain.

"It will be quite proper then to analyse those results and if the Conservative Party has not made net gains on May 1, then of course there will be searching questions at the inquest afterwards.

"There is concern about the performance of the Conservative Party in opposition. We are not yet providing the opposition that Britain needs at a time when the Government itself is making so many blunders and is acting in an increasingly discredited way."

But Bernard Jenkin, the North Essex MP who was Mr Duncan Smith's campaign manager during his battle to become leader of the Conservatives, said last night the Tories should be concentrating on the forthcoming spring conference and local elections.

"I think Iain has been getting on with party matters, setting out a number of new policies, particularly on public services," he added.

"All this current briefing should stop. We are never going to be elected unless we are a united party and are seen by the public to be rowing amongst ourselves.

"I am very sorry that people are speaking out in the way that they are because it is very damaging for the leadership and that is very damaging for the party. We should instead be concentrating on damaging the Labour Party."

David Ruffley, the MP for Bury St Edmunds, said there was no appetite for a leadership contest among grassroots members.

"I do not believe that it would be very sensible to have a challenge when this country is on the verge of war. I think the British public would take a very dim view of that," he added.