for the Tory base, including the ex-UKIP influx of Tory Party members.
Not only does the current make-up of Parliament mean the votes aren't there to allow it (so, unless Johnson intends to call an election while Parliament is in summer recess immediately if he's elected, it won't happen), the Cabinet already knows the UK won't be prepared:
Boris Johnson Brexit plan difficult or impossible, says Philip Hammond
Boris Johnsons Brexit plan is impossible as the UK will not be able to leave the EU with a deal or without a deal by the end of October, Philip Hammond, the chancellor, has said.
Hammond, who is fighting against no deal, cast doubt on the viability of the Brexit promises of Johnson and other Tory leader contenders such as Dominic Raab as he gave a speech in Westminster.
He said many of the candidates were pledging things that they could not deliver during their campaigns which they may have to go back on later.
Asked whether Johnsons plan to leave on 31 October would work, he said: I dont think so
I think its not sensible for candidates to box themselves into a corner on this. Parliament will not allow a no-deal exit from the EU and our experience has suggested it may not be that easy to secure a deal in parliament.
https://www.theguardian.com/politics/2019/jun/12/boris-johnson-brexit-plan-ifficult-or-impossible-hammond
Brexit: Leaked cabinet note admits UK not ready for no-deal exit on October 31, blowing hole in Boris Johnson leadership pledge
It will take six to eight months to build up supplies of medicines for a no-deal Brexit, a leaked cabinet note says undermining Boris Johnsons threat to crash out of the EU on 31 October.
The warning says the pharmaceutical industry needs that period of help from the government to ensure adequate arrangements are in place to build stockpiles of medicines.
It also says that it would take at least 4-5 months to make traders ready for the new border checks that might be required, including incentives to register for fresh schemes.
...
It states that, while government departments had delivered around 85 per cent of their core no-deal plans, many of those provided only a minimum viable level of capability.
https://www.independent.co.uk/news/uk/politics/brexit-no-deal-boris-johnson-medicine-supply-drug-stockpile-nhs-a8955021.html