MPs will keep voting until only two candidates are left. This knockout stage is important, since MPs who back the weaker candidates in the first rounds will be free to support other candidates later on. Expect plenty of horse trading. Some defeated candidates may ask their supporters to back another candidate - but there is no way they can make this happen. Votes continue to take place, on Tuesdays and Thursdays, until there are only two candidates left.
Members can choose between the two candidates who survived the parliamentary vote.
The one with the most votes becomes leader. It is almost certain that Michael Portillo will win the parliamentary vote - but that does not mean he will win in the end. No one knows quite how many Conservative members there are or which candidate they are most likely to back. It's widely assumed that members would choose a rightwinger - but last time they were surveyed, before the 1997 contest, most members came out in favour of Ken Clarke, the most leftwing candidate. A recent poll confirmed this result may be repeated.