CONSERVATIVE MP John Greenway today admitted demanding a vote of confidence in Tory leader Iain Duncan Smith.

The Ryedale MP has written to Sir Michael Spicer, chairman of the Tories' backbench 1922 committee, supporting a leadership challenge.

He acted after warning Mr Duncan Smith he would demand a confidence vote "if the crunch came".

Today ex-frontbencher Mr Greenway said: "We have to have this vote to draw a line on this. I think he should have called this himself. He hasn't done it, so those of us who think there has to be a vote of confidence are left with no choice."

His admission comes a day after Mr Duncan Smith called on plotters working to overthrow him to either gather by tomorrow the 25 names needed to trigger a leadership challenge or fall in line.

Mr Greenway became the fourth disgruntled Tory MP to write formally to Sir Michael calling for a ballot. The others are former Shadow Cabinet Minister Francis Maude, ex-government whip Derek Conway and former frontbencher Crispin Blunt, who called for a leadership contest in May. A fifth MP who wished to remain anonymous today confirmed he too had called for a ballot. Mr Maude - the most senior MP to break cover - urged people to "either step up or shut up" this week. He said that he believed the Conservatives "would do better under a different leader".

If 25 MPs write to Sir Michael demanding a confidence vote, a ballot will automatically be called.

Mr Duncan Smith would need a majority of the votes cast in a secret ballot by his 165 MPs to survive.

Failure to secure that would trigger a leadership contest in which he could not stand. But if there is a confidence vote and the Tory leader wins, he cannot face a further challenge for another year.

The Tory leader last night suggested he would stay on even if he won a confidence vote by only one MP. "You can only run things in accordance with the rules. The rules are if the 25 names go forward, then there is a vote of confidence. The winner is the winner in the confidence vote," he said.

Mr Duncan Smith added: "Wednesday is an excellent moment to draw the line, one way or another, and move on or settle this."

Updated: 14:39 Tuesday, October 28, 2003