The tea-time deadline will bring to an end the eight-week contest to replace Boris Johnson in Downing Street, after the outgoing PM announced his resignation following a revolt by Tory MPs.
Around 160,000 Tory members have been given a vote in the final stage of the leadership contest – between Ms Truss and Mr Sunak – with the result of the ballot to be announced at an event in Westminster at lunchtime on Monday.
Ms Truss is widely predicted to be crowned the new Tory leader with the Foreign Secretary expected to use this weekend to continue her preparations for entering Number 10.
But an ally of Mr Sunak, the former chancellor, this morning insisted the race was still ‘neck and neck’ and the result not ‘cut and dried’.
A win for Mr Sunak would shock Westminster and the wider country after polls have consistently put Ms Truss ahead of her rival in the leadership battle.
Whoever is the announced the victor on Monday will have a whirlwind 48 hours at the beginning of this week as they start their premiership.
They will first have to travel to Balmoral in Scotland on Tuesday to be formally appointed as PM by the Queen.
Traditionally during Her Majesty’s 70-year reign, the Queen has appointed new premiers at Buckingham Palace.
But Royal aides have decided to spare the monarch the journey to London next week in case she is suffering from mobility issues on the day.
The new PM is then expected to make their first address to the nation from outside the door of Number 10 on late Tuesday afternoon – following their return from their audience with the Queen.
They will then likely begin appointing top ministers to their new Government prior to holding their first Cabinet meeting on Wednesday morning.
It is widely assumed, should Ms Truss become the next PM, that Kwasi Kwarteng will become her new Chancellor.
A first Prime Minister’s Questions will then await the incoming premier at noon on Wednesday, when they will first do battle with Labour’s Sir Keir Starmer.
The new PM – who will face immediate decisions over how to give extra support to families during the cost-of-living crisis, how to prepare the NHS for winter, and how to continue British support for Ukraine – will have fewer than 1,000 days before they need to call a general election.
The new Tory leader will also face a challenge to reunite their party after this summer’s bruising leadership contest, which has been marked by a series of ‘blue on blue’ attacks.
This weekend, the Foreign Secretary is likely to be holding final discussions with her team about key appointments, what she will say in her first words as PM, and how she will respond to the immediate challenge of soaring energy bills.
But, despite the widespread expectation that Ms Truss will be travelling to see the Queen on Tuesday, those in Mr Sunak’s camp were today still holding out hope of a shock result.
Kevin Hollinrake, a supporter of the former chancellor and MP for Thirsk and Malton, insisted Mr Sunak had been proving popular with Tory members during the leadership campaign.
He told Sky News: ‘I’ve seen some of the polls and national polls. I think it’s quite hard for pollsters to determine who is a Conservative member and who is not because there’s not an open database.
‘But I know who mine are. I polled my 700 members, 239 of them responded, so about a third of them responded, and Rishi got an eight-point lead.
‘And I’ve seen similar kind of polls around different constituencies around the country. So I don’t think he’s cut and dried. I think he’s probably neck and neck.’
Source: The Dailymail