Boris Johnson and Jeremy Hunt face a series of hurdles in the race to Number 10 over the coming weeks.
Here are some of the key events:
– June 26
A “digital hustings” hosted by journalist Hannah Vaughan Jones has been organised by Conservative Campaign Headquarters (CCHQ), allowing members of the public to submit questions to the two men competing to be the next prime minister.
– June 27
The second hustings for Tory members will take place in southern England. The first event, in Birmingham on Saturday, saw activists jeer host Iain Dale as he asked Mr Johnson about the row with girlfriend Carrie Symonds that saw police called to their home.
– June 28
Another chance for Tory members to see their next leader and prime minister in action, with a hustings in south-west England.
– June 29
Two hustings – in the Lakes and Borders region and north-west England.
– July 1
Date offered by Sky News for a head-to-head debate after Mr Johnson refused to participate in one scheduled for June 25.
— Kay Burley (@KayBurley) June 24, 2019
– July 4
Hustings in the Yorkshire and Humber region.
– July 5
Two hustings, in north-east England and Scotland.
– July 6
Two hustings, in the East Midlands and Wales.
– July 6-8
The estimated 160,000 Conservative members who will decide the next prime minister should receive their postal ballots.
– July 9
Mr Hunt and Mr Johnson will go head-to-head in an ITV debate hosted by Julie Etchingham.
— Boris Johnson (@BorisJohnson) June 20, 2019
– July 11
Hustings in south-east England.
– July 12
Hustings in Gloucestershire.
– July 13
Two hustings, in Cambridgeshire and Essex.
– Week beginning July 15
The two leadership contenders are expected to take part in a debate organised by The Sun.
– July 17
The final hustings will take place in London.
– July 22
The ballot closes at 5pm, with the Conservative backbench 1922 Committee’s Dame Cheryl Gillan and Charles Walker acting as returning officers.
– July 23
The announcement of the new Tory leader will be made – although the victor does not automatically become prime minister at that point.
– July 24
Theresa May is expected to take her last session of Prime Minister’s Questions before heading to Buckingham Palace to offer her resignation to the Queen.
The new leader will then head to the palace to formally become the new prime minister – the 14th of the Queen’s reign.
But the timing of the changeover is a matter for Buckingham Palace to decide.
– July 25
The last day the Commons is due to sit before the summer recess, it could provide an opportunity for Labour to table a motion of no confidence in the new premier.