Kenneth Clarke and Liam Fox face the threat of elimination in the first round of the Tory leadership contest today.
Former chancellor Clarke and Dr Fox are battling to survive a knockout ballot of Conservative MPs. David Davis and David Cameron are the other two contenders.
Former front-runner Mr Davis is also under pressure to deliver his 66 publicly declared pledges in the private ballot.
With Mr Davis and bookies' favourite David Cameron way ahead on public pledges, the fight is on for third place.
Pro-European Mr Clarke told fellow Tory MPs that party activists wanted him in the last two. "I actually sense that what the membership want is David Cameron and myself to go forward at the end," Mr Clarke said.
"We plainly have overwhelmingly more public support than the other two. Obviously the Conservative Parliamentary Party must first of all pronounce."
Dr Fox invited backbenchers to take part in an "intellectual renaissance". He said: "While the front bench must be bound by collective responsibility, backbenchers must be given the freedom to roam," he said.
PA