By Graham DinesPolitical EditorTHE Conservative Party leadership contest is officially under way after Sir Michael Spicer, chairman of the 1922 Committee of Tory MPs, received Mr Howard's formal letter of resignation.

By Graham Dines

Political Editor

THE Conservative Party leadership contest is officially under way after Sir Michael Spicer, chairman of the 1922 Committee of Tory MPs, received Mr Howard's formal letter of resignation.

Five candidates have declared they will run for leader - David Davis, David Cameron, Sir Malcolm Rifkind, Liam Fox and Kenneth Clarke. Other potential contenders have until next Thursday to throw their hat into the ring, and there is a possibility that Shadow culture secretary Theresa May will decide over the weekend to stand to ensure women are represented on the ballot.

Arch Eurosceptic right-wingers Bill Cash and Edward Leigh are also weighing up their options.

The timetable for the contest was outlined by Sir Michael yesterday. “Nominations, with a proposer and seconder, must reach my office in the House of Commons in writing by noon on Thursday October 13.

“They must include a signed statement by the candidate that he or she is willing to stand as a candidate for the leadership of the Conservative Party and in so doing will abide by the Party's constitution, the rules of the 1922 Committee and the regulations published pursuant to those rules.

“Assuming more than two valid nominations are received, the first ballot will take place on Tuesday October 18.”

MPs will eliminate candidates until only two remain and those candidates will be voted on by the 300,000 Conservative Party members. The result will be announced in early December

Two more MPs have decided to back Sir Malcolm's candidature. The former Foreign Secretary has won the support of Michael Ancram, the Deputy Leader of the Conservative Party, and senior backbencher Sir Patrick Cormack.

Mr Cameron has eclipsed Mr Davis as bookmaker William Hill's favourite at 4/5 odds-on after the shadow home secretary's disappointing speech in Blackpool. Mr Davis is in second place with odds of 7/4. Mr Clarke is 9/2 and Dr Fox 12/1, and Sir Malcolm 66/1.

Hill's spokesman Rupert Adams said: “We have been overwhelmed by the money for David Cameron and even though his price is 10 times shorter than it was on Monday, punters continue to see value in his price with four-figure bets placed in all parts of the country.”