Long-time favourite David Davis has sought to play down a negative reaction to his conference pitch to be the next Conservative Party leader.
The general newspaper verdict was that his speech disappointed, while rival candidate Sir Malcolm Rifkind told the BBC he must now be "very worried".
But Mr Davis said he was still "odds-on favourite" to become leader and that he would face "tougher tests" in future.
Current leader Michael Howard ended the conference with a call for unity.
In his speech Mr Howard praised the performances of all the candidates and urged the party to unite behind whoever won the contest.
'Must be worried'
Mr Davis, the shadow home secretary, told BBC1's Breakfast: "One of the tests of leadership is going through the odd difficult day."
Conservative members themselves had been "very impressed" by the content of his speech, while the contest so far had been "productive".
But another leadership contender, Sir Malcolm Rifkind, said of Mr Davis: "He must be very, very worried because he was speaking to a party of Conservative enthusiasts who wanted to will him to succeed.
"If he was unable to achieve that one has to ask the question how would he deal with Gordon Brown over the next four years."
However, in his speech, Mr Howard will avoid detailed comments on the five-man leadership race.
He will stress the need for the party to continue renewing itself in preparation for the next election.
Party bosses 'happy'
Before the conference started there was much media speculation that the manner of Mr Howard's resignation - with a long period of campaigning before a successor was chosen - could prove damaging.
But party bosses claim they are happy and that the event was an overall success.
After Thursday the focus will move to the Commons, where MPs will decide who to back in the first leadership ballot on 18 October.
David Cameron and Kenneth Clarke from the left of the party both impressed the conference with their performances.
And, just hours after Mr Davis set out his stall, right-wing candidate Liam Fox was given a better reception by the conference.
Although some commentators claim Mr Davis's performance might harm his chances, he is still the front runner with more MPs - 66 - declared for him than any other candidate.
Mr Davis dismissed suggestions that the poor reception given his speech would cost him support.
He said he was "pretty confident" of making it through to the final ballot of the membership and of then winning the leadership.
Mr Davis told BBC Radio 4's World at One: "It wasn't a comfortable day, but the effect, I suspect, is rather overstated.
"It has had no effect on the MPs' voting intentions. The 66 is still 66. There will be more coming at some point in the future, so it doesn't affect that at all."