The result of the second ballot for the Conservative leadership is set to be announced within the next hour.
Tory MPs have finished voting in the latest stage of the process for deciding the UK’s next prime minister.
Any of the six remaining candidates will be eliminated from the contest if they come last or fail to secure at least 33 votes.
Those remaining in the race will take part in a live BBC debate in central London on Tuesday evening.
Remaining candidates will face further ballots later this week, where the bottom-ranked MP will be knocked out until only two are left.
The final two names will then be put to a postal vote of the 160,000 Tory party members, beginning on 22 June, with the winner expected to be announced about four weeks later.
All 313 Conservative MPs were expected to take part in the second ballot in the Houses of Parliament, which ended at 17.00 BST.
All the contenders – Boris Johnson, Jeremy Hunt, Michael Gove, Dominic Raab, Sajid Javid and Rory Stewart – cast their ballots in the first hour of voting.
Mr Johnson, the former foreign secretary and Mayor of London, remains the man to beat in the race after topping the first ballot earlier this month with 114 votes.
The BBC’s chief political correspondent Vicki Young said there were “a lot of nerves around” although the “one certainty” in Tuesday’s poll was that Mr Johnson would again finish top.
Former cabinet minister Andrea Leadsom – who was knocked out in the first round – has given him her support as have ex-ministers Tracey Crouch and Damian Green, who switched from Matt Hancock after he withdrew last week.
Current Foreign Secretary Mr Hunt, who came second with 43 votes, and Environment Secretary Mr Gove, who was third with 37, in the first round should make it through to the next ballot on Wednesday if their support holds firm.
Mr Raab, who received 27 votes, and Home Secretary Mr Javid, who received 23, told reporters on Monday they were confident of making it through to the next round.
International Development Secretary Mr Stewart, who received 19 votes in the first ballot, said he had the necessary 33 backers to stay in the race “if they do what they say”.