The Conservatives “failed to deliver” on their promises and lost the trust of voters, said the former cabinet minister Robert Jenrick, who did not rule out running for the leadership of his party. Two other potential leadership candidates – Victoria Atkins and Suella Braverman – said on Sunday it was not the time to declare their intentions but that a postmortem was now needed in the party. Writing in the Telegraph, Braverman said the Conservatives “failed in office and deserved this result” and warned against complacency. “I say again, whatever some of my colleagues think, the voters aren’t mugs: they saw what we did in office and ignored what we insincerely said while campaigning,” she said. Jenrick, speaking on the the BBC’s Sunday with Laura Kuenssberg, said he also believed that delivery – especially on immigration – was key to the party’s loss. “The Conservative party is a broad church, but it’s got to have a common creed,” he said. “The reason that we lost the trust of millions of people across the country is not because we were too leftwing or rightwing or had this slogan or that slogan. But fundamentally, because we failed to deliver on the promises that we made to the British public. “We promised that we would get Brexit done and that we would deliver a strong economy, a strong NHS and secure borders … We did not deliver the level of growth and taxation that Conservatives expect, the quality of service in the NHS that the public need, and above all the secure borders and controlled, reduced migration that we promised and which we need to deliver.” Atkins, a key ally of Rishi Sunak who was health secretary in his government, said there was still potential for the Conservatives to regain strength quickly. “I do observe that the support for the Labour party in this election has spread very thinly, a little bit like margarine,” she said. “And so I think there’s a real opportunity for us as a party. Once we have reflected, once we have absolutely taken on board those lessons and acted on them, I think there’s a real job for us to do to rebuild our party and we will do that.” Atkins said the country was “instinctively Conservative” and added: “They want lower taxes. They want to build a better future for their children. They want us to help them thrive in their personal lives.” Braverman in her Telegraph piece warned against complacency. “So many of the so few colleagues who survived letting Rishi be Rishi still don’t get it … Half our votes lost, two-thirds of our MPs, and already there’s complacency,” she wrote. “We Tories need to face facts: we failed in office and deserved this result. Any analysis of the worst general election in our history that doesn’t start there is self-comforting or self-serving.” Sunak has said he will stay on until the Conservative party leadership election has at least begun – though it remains unclear if he intends to stay until it is over. The party must assemble a new backbench committee that can confirm the rules for the contest; the long-serving chair of the 1922 Committee, Sir Graham Brady, did not stand for re-election. Both Jenrick and Atkins said it was not the time for them to declare their leadership intentions. Atkins said she was speaking out “not to talk about leadership, because this is not the moment for this. We need to show the public that we understand they have sent us some very, very loud messages, that we are listening, that we are reflecting and then we as a party need to get together and unite and work out what we want for the future.” Jenrick, who quit as immigration minister under Sunak, said: “I honestly don’t think that three days on from a general election in which we’ve just lost so many of our friends and colleagues that it is right to have self-indulgent conversations like this. “I care about the Conservative party. I’ve been a member of this party since 1997, when I was 16 years of age, I’ve been with it through thick and thin. I want to ensure that it has the right diagnosis of what’s gone wrong. And that diagnosis is not about personalities. It’s about principles and ideas.”