The six Conservatives vying to become Britain’s prime minister face off in the second round of voting on Tuesday, with the final pair to be decided by the end of the week.
The outcome of the leadership battle could determine under what conditions Britain leaves the European Union. It is currently scheduled to leave on October 31.
All of the party’s 313 MPs can take part in the secret ballot in the contest to replace outgoing leader Theresa May, with further rounds scheduled to whittle the list down to a final two, who will face the party’s 160,000 grassroots members.
Boris Johnson, the former foreign minister and leading Brexit campaigner, ran away with the first round of voting last week, winning the support of 114 MPs — more than twice the number of votes won by his nearest challengers.
Johnson has said he is open to leaving the EU on October 31 without a formal deal between London and Brussels but would prefer to secure one by the deadline.
Opponents of “no-deal” say it would cause economic chaos as Britain breaks up with its top trading partner.
Any candidate failing to win the support of at least 33 MPs on Tuesday will be eliminated, with the worst performing contender dropping out if they all reach the threshold.
The result will be announced around 6pm (1700 GMT).