MPs are to be given the opportunity soon to vote on various options for the make-up of the second chamber. A 50-50 split between nominated and elected members or a 60 per cent elected House are regarded as the most likely outcomes.

After the Commons decision, legislation reducing the size of the Lords by a third and providing for the eventual abolition of life peerages will be introduced in the session of Parliament beginning on November 15.

It is fully expected by ministers that the Bill will ultimately founder in the Lords irrespective of whether a consensus has been agreed by the parties. Ministers are confident that a way will be found to ensure that this time MPs reach a firm decision. In the last series of votes all the options were rejected.

If, as expected, the Bill is blocked in the 2007 session, it will be reintroduced in the same form at the start of the 2007-8 session and pushed into law under the Parliament Act.

But Jack Straw, the Leader of the Commons, who is in charge of the reform, was given a rough ride by Labour peers when he talked about his plans last Wednesday.

Mr Straw, who was unable to give details because they have yet to be approved, was criticised for keeping peers in the dark. and at least three peers, including the Labour peer Lord Tomlinson, told him it that was the wrong time.

There were warnings that a Bill in the next session would clog up the parliamentary timetable and many peers voiced worries about their own future.

However, both Tony Blair and Gordon Brown believe that by the next election, when Labour will have been in power for 12 years, the party should have carried out its pledge to reform the second chamber.

For Mr Blair a Bill in the next session would be seen as part of his legacy. Mr Brown would like to go to the country with reform in place so that the first elections to the Lords could take place on the same day.

The Times has been told that the most likely plan is for the changes to be phased in over a number of parliaments so that life peers were not “sacked”. There would be severance packages for some.

However, next session’s Bill will abolish the remaining 92 hereditary peers.

Mr Straw is expected to propose that the elections to the Lords are based on the present boundaries for the European elections. Members of the second chamber would be allowed to sit for no more than three parliamentary terms.

Mr Straw will put forward a White Paper next month outlining the reforms. A reduction in the Lords from 741 to about 450 is foreseen. No single party would have an absolute majority. A new commission of nine members would ensure that the chamber reflected the religious, racial and gender balance of the country.

But Sir Patrick Cormack, a senior Conservative MP, described the plan as “a prescription for constitutional mayhem, setting the two chambers against each other”.

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