Tory MPs rather than voters are likely to remember the leadership contest insults for longer, according to a Conservative pollster.
Lord Hayward, a former MP and current Tory peer, believes the tone of the campaign will have a short-term impact on the wider electorate, although other issues will be more important to them by the next general election.
But the “more immediate, difficult and possibly slightly longer-lasting” impact of the campaign will be within the Conservative parliamentary party itself, Lord Hayward added.
This will require either Rishi Sunak or Liz Truss to create the circumstances under which the “previous frictions disappear”, he said.
Both candidates used the first head-to-head television debate on the BBC to trash each other’s economic policies and raise questions about their records on other issues, including China.
At one stage, Ms Truss declined to give Mr Sunak fashion advice when asked about criticism made by one of her supporters – Culture Secretary Nadine Dorries – about his expensive taste in clothing.
Allies of the pair have not been shy in pushing the cause of their candidate, with those linked to Ms Truss reported to have said Mr Sunak had demonstrated “aggressive mansplaining and shouty private school behaviour” during the debate.
Polling among Tory members suggests Ms Truss is the frontrunner to replace Boris Johnson.
Lord Hayward, asked whether the tone of the campaign will have an impact on wider voters, told the PA news agency: “In the short-term it does but in the longer-term, if one’s looking towards the next election, there’ll be issues that will have arisen that will be more important for voters at large.
“Clearly the more immediate, difficult and possibly slightly longer-lasting impact is the element of friction within the Tory parliamentary party and for whatever the new cabinet is until things settle down.
“Some of that will last for longer than other things, but the duty of any incoming new party leader is to create the circumstances under which the previous frictions disappear.
“Now that is difficult and Boris certainly didn’t do it, he created a first cabinet which was all his mates to the extent that somebody like Penny Mordaunt and several others were excluded, there was no attempt to bring people together.
“It will be difficult because some of the strong language by people’s supporters particularly will not be forgotten, and the decision will have to be taken by the new leader as to the extent of the effort they make to bring people together and therefore disregard what has been said by supporters.”
Lord Hayward said both campaigns had been “as expected” given what the polls are saying.
He explained: “Rishi has to be more aggressive because the polls are showing him behind, it’s an art of being aggressive without being unpleasant and that’s always difficult.”
Lord Hayward also stressed the importance of the hustings of Conservative Party members, adding: “Particularly those that are taking place before the postal ballots go out will be influential.”
Postal ballots are set to arrive on Tory members’ doorsteps by August 5.
Patrick English, YouGov’s associate director of political and social research, said: “The public have a pretty dim view of Boris Johnson, Rishi Sunak, Liz Truss, and the Conservative Party and what we are seeing right now in terms of the leadership race is unlikely to change any of that at all.
“We estimate that around 40% of the public are currently following the race either fairly or very closely. That number will steadily rise as we get toward September.
“So, the public are paying attention, to some degree, but I doubt the ins and outs of debates and ‘who said what’ are really going to register. But the headlines do.”
