Tory MPs are to cast their first votes in the contest to replace Boris Johnson as party leader – and prime minister, the BBC reports.
After nominations closed, the eight hopefuls took part in a hustings event in Parliament as part of efforts to secure support from their colleagues.
They have to secure 30 votes in the first round to stay in the race.
The candidates for leader are: Kemi Badenoch, Suella Braverman, Jeremy Hunt, Penny Mordaunt, Rishi Sunak, Liz Truss, Tom Tugendhat and Nadhim Zahawi.
Voting will start at 13:30 with a result expected at 17:00 BST.
Further votes will take place over the next few days in order to whittle the number of candidates down to two.
About 160,000 members of the Conservative Party will then choose between these final two, with the winner due to be announced on 5 September.
Ex-Health Secretary Sajid Javid and junior minister Rehman Chishti failed to secure enough nominations – the support of at least 20 Tory MPs – and withdrew from the contest on Monday.