Ronald Reagan famously said that the 11th commandment was: “Thou shalt not speak ill of another Republican.”
It’s fair to say that the former US president would take a rather dim view of the current Conservative leadership contest.
Despite calls from some Tory grandees for a clean fight, the battle has become dirtier and dirtier as it has gone on.
Hardly a day goes by without another attack - sometimes on the record, but more often off - by one side on the other.
Just last night, a Truss campaign source said of Sunak’s plans to borrow in order to help people with soaring energy bills “intellectually, it’s as watertight as a sieve”.
The blue-on-blue sledging appeared to reach its lowest point yet this morning when Dominic Raab, a leading supporter of Rishi Sunak, said Liz Truss’s plan to prioritise tax cuts over “handouts” to the poor were an “electoral suicide note”.
But within hours, the Sunak camp went event further, accusing Truss of being “divorced from reality” for sticking to her hardline approach.
And as the September 2 deadline for votes to be in approaches, both camps will become ever more desperate - and vicious - in their attacks on the other.
But it’s not just in the leadership contest that the bitterness within the Conservative Party is coming to the surface.
The Privileges Committee’s probe into whether Boris Johnson misled parliament has also shown that the manner of the outgoing prime minister’s defenestration will be a running sore for a long time to come.
Uber Johnson loyalist Nadine Dorries accused the committee members - four of whom are Conservatives - of conducting a “witch-hunt” against her hero.
Lord Goldsmith, another close ally of Johnson, also weighed in to the row, prompting committee member - and Conservative grandee - Sir Bernard Jenkin to accuse them of waging a “terrorist campaign” against a legitimate parliamentary inquiry.
There is no doubt that when the Conservatives’ new leader is announced on September 5 the party will rally round and profess their loyalty.
They did that with Theresa May and also Boris Johnson, and look how their leaderships ended.
Whoever ends up winning this time is likely to find that leading the country is a lot easier than leading their own party.