Horsham MP Francis Maude last night led the charge to oust beleaguered Conservative Party leader Iain Duncan Smith.

At least 25 backbench Tory MPs rallied to the cry, triggering a confidence ballot on the leader's future to be held later today.

If Mr Duncan Smith does not win a majority in the 3.30pm vote of all 165 Tory members he will be forced to step down, triggering a lengthy battle for succession.

Mr Maude, a former treasury minister and now a shadow chancellor, was the first of the so-called "plotters" to admit he had sent a letter to 1922 Committee chairman Sir Michael Spicer calling for the ballot.

His public declaration was accompanied by those of John Greenway, Derek Conway and Crispin Blunt.

Within hours, the 25 MPs needed to trigger the vote had done likewise.

Mr Maude said: "I put my cards on the table. I have formally asked for a vote of confidence to be called. Personally, I believe we would do better under a different leader and I will vote accordingly."

The other Tory members who sent letters to Sir Michael remained anonymous last night.

Peter Bottomley, West Worthing MP, said he would not comment until after the ballot, but he added: "Francis Maude's intervention may have been influential in getting confidence among other MPs for the ballot, which Iain Duncan Smith says he welcomes."

Greg Barker, MP for Bexhill and Battle, said he would listen to his constituency members before deciding whether to back Mr Duncan Smith.

He told The Argus: "This needs to be brought to a conclusion as quickly as possible and we must draw a line under this pointless internal battle.

"We have a big job to do to take on Tony Blair. I will be listening very carefully to my party members in Bexhill and Battle over the next 24 hours before coming to a decision. Whoever wins, we have to unite behind him or her."

Tim Loughton, MP for East Worthing and Shoreham, said: "I'm not speaking at all now. I will be later in the week."

It is thought unlikely Nicholas Soames, MP for the neighbouring Mid Sussex constituency, is among the 25.

While he has not been a vociferous supporter of Duncan Smith, and backed Michael Portillo in the 2001 leadership bout, he recently admitted he shared the leader's "disgust" at colleagues working from the shadows to drive wedges in the party.

Despite the silence from his party colleagues, Mr Maude said he was convinced the majority of Tory MPs wanted a change of leadership.

He said: "Iain and his team may be quite right that this is just a few malcontents.

"I don't think that is right but this is an opportunity to show one way or the other.

"If there is widespread concern then a vote will be triggered and we can go through the duly laid down process. If not, then we must rally behind Iain and endeavour to make a success of his leadership."

Shadow secretary of State David Davis sparked fresh speculation about his leadership plans last night when he stayed away from Duncan Smith's doorstep declaration that he would fight to stay on as leader.

The statement followed an emergency meeting of his shadow Cabinet to discuss the confidence vote.

Duncan Smith told shadow ministers it was up to them as individuals to decide how they were going to vote.

The Conservative leader told them: "I believe I have earned the right to take this party into the next election. But I can't do that unless this party wants to be led."

And he warned of the perils of a three-month leadership election, saying it would "destroy the confidence of our party in the country and lead to disastrous results at the next election."

Deputy leader Michael Ancram responded on behalf of the Shadow Cabinet saying: "We all wish you luck."