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.

Sydney Airport flights disrupted due to air traffic controller shortage
Philippine firefighters enter charred ferry as search continues for dozens missing
More US lawmakers seek AI rules after Anthropic researchers warn of extinction
Fire in rebel-held east Congo kills 24 schoolchildren
Trump says he does not regret Iran war despite potential impact on elections
Trump touts $5,000 payout if Republicans win as Vance waits in wings
Search expands after Philippine ferry fire kills five and leaves dozens missing
Trump says Iran war to end after US midterm elections
