With the clock ticking down to tonight’s blockbuster leaders’ debate, the five hopefuls are scrambling to shore up support in the parliamentary party.

Rishi Sunak, Penny Mordaunt, Liz Truss, Kemi Badenoch and Tom Tugendhat will face off on Channel 4 from 7pm to 9:30pm, with Krishnan Guru-Murthy presenting.

Simply making it to the debate stage is great result for Badenoch and Tugendhat, whose public profiles will be given further boost. They have everything to gain and nothing to lose.

A live studio audience of floating voters will pose questions – and each candidate will have some they really don’t want asked. See The Hound.

The debate will give the public a sense of whether each of the five has the intellect and charisma needed for the top job. But the candidates’ primary audience will be the 353 Tory MPs whose votes they need to secure a place in the final two. Many will have already made up their minds. Others will be open to persuasion. The next round is on Monday.

All five challengers took part in a weird warm-up to tonight’s clash this morning – the first ever Zoom hustings, answering questions from readers of the ConservativeHome website.

They made – mostly veiled – attacks on one another, but the awkwardness of Zoom wasn’t conducive to a proper scrap.

In truth, it was a bit of a sideshow – each candidate’s focus will have been wooing fellow MPs.

Liz Truss – currently in third place – secured Lord Frost’s backing today after his take-down of Penny Mordaunt yesterday. Truss leapfrogged Rishi Sunak last night to become the bookies’ second-favourite after Suella Braverman – knocked out with 27 votes – threw her weight behind the foreign secretary. Most of her supporters will probably follow.

Team Truss believes her “natural ceiling” of votes is higher than Mordaunt’s, the assumption being that a lot more MPs would head to Truss from the Badenoch/Tugendhat/Braverman vote pool than to Mordaunt.

Yet the influential ERG group is still divided over whether to back Truss. There’s resentment in the ranks at the idea of backing someone who campaigned to stay in the EU. The group’s chairman, Mark Francois, sent a WhatsApp message to his colleagues last night, saying: “I do hope we feel able to unite firmly behind Liz”. Andrew Lewer replied that he was backing Badenoch and that “MPs on this group will make up their own minds”.

Tonight’s debate will help them do just that. Two more televised debates will follow on Sunday and Monday night.

As the mercury heads towards 40°C in the next few days, candidates will need to keep cool and calm under the studio lights to avoid a meltdown. Easier said than done.