Contenders for the Conservative Party leadership are expected to go head-to-head in a televised debate for the first time since the race to succeed Mr William Hague began.
The candidates will pitch their campaigns on the same platform in a BBC Question Timespecial to be screened on Thursday night.
The five candidates declared so far are not likely to be joined by any latecomers, and the stage is set for the first round of voting next week.
The contenders - Mr Michael Portillo, Mr Kenneth Clarke, Mr Iain Duncan Smith, Mr Michael Ancram and Mr David Davis - have spent the last week stepping up their campaigns among Tory MPs whose backing is essential to win through to the final round.
The five will be whittled down through a series of ballots starting next Tuesday - supervised by the chairman of the backbench 1922 committee Sir Michael Spicer - until two names remain.
Some 300,000 party members will then select the winner through a postal ballot.
Last night, Sir Michael told rank-and-file MPs the leader would be declared on September 12th - just over three weeks before the party's conference in Blackpool.
Shadow chancellor Mr Portillo has been the favourite to win the race since he announced he would stand three weeks ago and is said to have the largest support among Tory MPs.
But several polls have put Mr Clarke in the lead among party members in the constituencies.
PA