The Conservatives should not have a protracted leadership debate as it would be a “waste of time” and could risk appearing self-indulgent, the Tees Valley mayor Ben Houchen has said. His comments came as former Conservative parliamentary candidates rounded on the former prime minister Liz Truss, who has attacked the leadership of Rishi Sunak in the failed general election campaign by saying he had trashed her legacy in office. Two ex-candidates, the former MP Conor Burns and the former Tory adviser Rupert Harrison, said Truss should stop her interventions. Truss wrote in the Sunday Telegraph that the Conservative party had “paid the electoral price” for her successor’s errors, but Harrison, a former adviser to George Osborne and Sunak who was beaten by the Lib Dems in the Bicester and Woodstock constituency, said: “As someone who just lost a seat, it was clear from the doorstep that her record was one of the main reasons we were so soundly beaten. No individual in history has done more damage to the Conservative party.” Burns, who lost the Bournemouth West seat to Labour, told LBC: “Those who are close to her [Truss] are letting her down by not telling her the truth. She is preposterous; she is toxic; she needs to be quiet.” The party is expected in the coming week to start the process to agree a timetable for the leadership contest. No one has yet formally declared their candidacy but those who are privately gathering support for a run include the former home secretaries Priti Patel and James Cleverly, the former housing secretary Robert Jenrick, the former security minister Tom Tugendhat and the former business secretary Kemi Badenoch, whom several polls have named as the party members’ favourite. A new poll of ConservativeHome readers put Badenoch as the favourite, ahead of Jenrick – the two candidates said to have gathered the most support from MPs. Jenrick wrote a piece on the website on Friday proposing big internal party changes in order to help rebuild. Braverman is said to have lost critical support in the party to Jenrick and came in fourth in the poll, behind the centre-right Tugendhat. Patel, a close ally of Boris Johnson, had the support of just 3% in the poll. Houchen, who is now the most senior Conservative in office, said the party was well aware of the potential leadership candidates and said he could not see why a contest would need to run much past party conference in October. “If we navel-gaze for too long, that’s going to turn off the public even more, because it again feeds into that perception that we’re more concerned about the ongoings of the Conservative party rather than what the public care about, which is: how do we help improve their lives?” he told BBC One’s Sunday with Laura Kuenssberg programme. Houchen said he had been contacted by a number of leadership candidates but had not yet decided who to endorse. A number of MPs and former MPs have said they think the party needs a longer period of introspection, perhaps as long as six months. “We do need to get there relatively quickly, because without a successful and competent opposition, I think parliament, in and of itself, starts to break down, doesn’t work as effectively as it could do,” Houchen said. “We need to make sure we find the right leader to navigate us through what is going to be a very, very difficult time to try and unite the party. “The next couple of years are going to be very difficult for the Conservative party to find itself again, what it means to govern effectively, what it wants to offer to the public over the next four or five years. And so the next 18 months are going to be a treacherous one for the Conservative party.” He said the party conference should “there or thereabouts” be the time for appointing a new leader. “I think certainly in the first half of October, we need to be getting into a place where we do have a leader in place. I think the honest answer is, we know, roughly … the likely candidates who are going to put themselves forward for the leadership contest … It’s pretty obvious. “They’re pretty well known to the Conservative party. We roughly know where they stand in the Conservative party spectrum … but the idea we need a long and protracted process that gets into some sort of existential crisis about what the Conservative party stands for and what these leadership contenders stand for would be a waste of time.” Houchen, who had been a key supporter in Sunak’s leadership campaign and was previously close to Boris Johnson, said he did not know who he would now support. “Absolutely, a number of the contenders have already been contacting me. And over the coming weeks I’ll be meeting with them because they’ve asked to meet with me to discuss their intentions, but we’ll have to wait and see what happens,” he said. “The Conservative party is very different to the one it was just a few weeks ago. And so, while those people are familiar to us, we also need to understand what their positions are on rebuilding the Conservative party.”