Voting is set to close later on Monday in the Conservative leadership contest.
Party members have until 5 pm UK time to vote for either Jeremy Hunt or Boris Johnson as their next Tory leader.
Johnson, who is the former mayor of London and the ex-Foreign Secretary, is widely considered to be the favourite in the race.
The UK's next prime minister will be announced on Tuesday, and he will take office a day later, succeeding Theresa May.

Iran rejects Trump's talk of negotiation as Israel and Iran launch airstrikes
Cyprus has opened discussion with UK over its bases, president says
Netanyahu seeks to avoid snap vote as Iran war gives no boost in polls
Luxury Paris hotel near Elysee reopens after fire forces brief closure
Germany renews push for sugar tax and energy drinks ban for children
No injuries reported as drone attack hits fuel tank at Kuwait's airport
US expected to send thousands more soldiers to Middle East
Philippines works with Washington to obtain oil from US-sanctioned countries
