The Conservative leader is resisting calls to step down ahead of schedule.
With unrest spreading among Tory MPs, who fear Michael Howard is now a "lame duck" having announced he is to quit in the autumn, the Tory chief insisted on Thursday he would stay until the autumn as planned.
"I set out a timetable very shortly after I indicated I was going to stand down," he told BBC Radio Kent.
"I've said that we ought to have a period to reflect on the best way forward for the party and learn the lessons of what happened at the election.
"There are proposals to change the rules and we have to see if we can get them through in September... and I said after the party conference I would step down. I think that's the right timetable and that's what I intend to do."
However he did concede in a letter to MPs that an announcement on changes to the party's constitution "could have been better handled".
And he revealed that he was also decoupling a vote on changes to the Tory leadership election rules from other constitutional proposals.
Earlier former party chairman Lord Tebbit had said Howard should go by the end of the summer instead, adding to rumours of discontent voiced by senior MPs.
Asked if Howard should be gone by the summer, Lord Tebbit told BBC Radio 4's Today programme: "That would be highly desirable.
"Then the new leader could come to the party conference with the authority of having been recently elected and having listened to what everybody said, with proposals to reform the constitution of the party."
'Limbo'
Former shadow minister Quentin Davies told the BBC Radio 4 World at One programme: "A great party, certainly a party in opposition, can't just go into limbo for six months, it can't go into paralysis. That is absurd.
"It is really up to us to make sure that we get a new leader and get the party moving again and get the opposition functioning as it should as soon as possible."
He said that it should be possible to put in place the new leadership rules in a "matter of weeks".
"If that happens I see no reason why we shouldn't actually have the process of electing a leader take place in July and have new leader of the opposition in place by the time the House rises for the summer recess," he said.
"That would give the new leader time to prepare the party conference and then we would be away."
MP Bill Cash also called on Howard to consider his position.
"The arrangements and proposals for the party rules have turned into a huge mess and a lot of people are extremely angry about the lack of consultation," he told the ITV News Channel.
"Therefore the situation has developed in a way that was in many respects predictable once they decided to go down that route. It has now turned into a much bigger question - what do we do next?
"Michael should consider his position in the light of the present circumstances. We cannot go on with this problem of the party rules dominating the agenda into the indefinite future."
Caution
Derek Conway, a supporter of likely leadership candidate David Davis, told ITV News on Wednesday that many people were unhappy at the prospect of Howard staying on until December.
Asked whether MPs were considering collecting 30 names needed to bring about a vote of confidence, he said: "We are counselling caution rather than action, but groups of people are talking about it."
Earlier in the day, leading party moderniser and former shadow education secretary Damian Green had said Howard's authority was "ebbing away".
"How long can it take for 200 politicians to organise an election? It certainly won't take seven months," he said.
The Telegraph newspaper, influential in the party, said the revolt "is a sign that [Howard] is rapidly losing authority in the shadow Cabinet and the party at Westminster".
At a press conference on Wednesday, Howard had dismissed Green's remarks as the voice of just one MP, but that was before Conway and others came forward.
Mutiny
The mutiny was sparked by planned reforms of the Conservative constitution, which MPs felt had been presented to them as a fait accompli.
A stormy meeting of the backbench 1922 committee on Tuesday saw the leader attacked over reports that MPs were to be set performance targets and bound by a new loyalty contract.
However Howard insisted the meeting was merely an "entirely legitimate" "exchange of views" and that contracts for MPs had never been considered.
He argues he is staying on in order to oversee changes to the leadership election rules, giving back to MPs the final say, before he steps down.
