Votes are being counted to decide the next Tory leadership candidate to be eliminated from the race.
The contest has become a three-way battle to face Rishi Sunak in the run-off to be the next prime minister.
With the former chancellor comfortably ahead in the Tory leadership contest, Penny Mordaunt, Liz Truss and Kemi Badenoch remain in the hunt for the second place on the ballot that will go to Conservative Party members over the summer.
Ms Badenoch would appear to be the most vulnerable candidate after finishing fourth in the previous round of voting.
Ms Mordaunt dropped a vote in the third ballot on Monday evening but was still able to fend off a challenge by Ms Truss to retain her second-placed spot, receiving 82 votes.
Ms Truss picked up seven votes to reach 71, while Ms Badenoch gained nine to reach 58.
Mr Sunak, who has unveiled a suite of policies to tackle crime, gained another 14 votes to reach 115, just five short of the 120 which will guarantee him a place in the final two.
The Mordaunt, Truss and Badenoch campaigns will spend the day attempting to woo Tom Tugendhat and his supporters following the Foreign Affairs Committee chairman’s elimination from the race.
The 31 votes up for grabs could prove decisive in shaping the rest of the race, with his support thought likely to head to Ms Mordaunt or Mr Sunak than the more right-leaning Ms Truss or Ms Badenoch.
Voting takes place between noon and 2pm, with the result due at 3pm.
Ahead of the vote:
– Mr Sunak promised harsher sentences for criminals who refuse to attend court for their sentencing hearings and a crackdown on grooming gangs.
– Ms Truss promised to increase defence spending by 2030 and strengthen the intelligence services.
– Ms Mordaunt used a Daily Telegraph article to promise she would ditch housing targets if she enters Downing Street, saying they have been “tested to destruction”.
– Boris Johnson used his final Cabinet meeting as Prime Minister to say the net-zero policy to tackle climate change is the “right thing to do” even if it is “unfashionable”, after criticism from the leadership contenders.
– Senior backbencher Tobias Ellwood, a supporter of Ms Mordaunt, had the Tory whip removed after failing to back Mr Johnson in a confidence motion on Monday.
Mr Tugendhat turned up to vote along with a group of his allies, but refused to say which who he was backing.
But a Mordaunt campaign insider said: “Don’t forget that lots of Tom’s backers are good friends of Penny and her One Nation endorsers.”
The message to Mr Tugendhat’s supporters is that “Rishi has all the support he needs and it’s time to get behind her” to ensure Ms Mordaunt is in the final two.
Meanwhile, Ms Mordaunt said she remains “committed” to Mr Johnson’s flagship levelling-up agenda amid concerns that the high-investment policy could be shelved for less costly policies once he leaves office in September.
Transport Secretary Grant Shapps, who is backing Mr Sunak, insisted on LBC radio that the former chancellor is a “huge fan of levelling up”.