Conservative MPs are about to make a renewed push for the UK to leave the European convention on human rights (ECHR), amid reports that Rishi Sunak is considering the move in order to allow a harsh crackdown on migration. The proposals were backed by the home secretary, Suella Braverman, during her leadership campaign over the summer. The Guardian has been told the policy is being pushed by a number of ministers, several of whom said they would like to see it form part of the Tory manifesto if it can’t be enacted before the next election. The decision to pull the UK out of the ECHR without an electoral mandate is likely to cause deep consternation in parts of the party – and would also face challenges in the House of Lords. Sunak is reported to be considering the controversial move as he prepares to set out new legislation to curb migration, which will ban anybody who comes to the UK irregularly from applying for asylum and then deport them as soon as possible, though the UK currently has a significant backlog. A new immigration bill is expected to be introduced within weeks. The move would be considered if the courts strike down that legislation, the Sunday Times reported. Sources admitted it would be unlikely before the next election. In June last year, the first deportation flight of asylum seekers to Rwanda was abandoned after a dramatic 11th-hour intervention from the ECHR, which rules on individual or state applications alleging violations of the civil and political rights set out in the European convention. Simon Clarke, the former cabinet minister, said it was “completely right” to consider withdrawal. “It is a fundamental question of trust and competence that we should very significantly curb illegal immigration into the UK. “We hear a great deal about how the UK played a key role in drawing up the convention, but the issues now being litigated under the ECHR were not in contemplation post world war II. Our human rights architecture is being abused by criminals to endanger the lives of desperate people. “We also hear a lot about how leaving the ECHR would embolden our adversaries. With respect, I don’t believe Putin will be influenced in his madness by whether or not we subscribe to the convention. Plus our actions to defend freedom are the ultimate measure of our values.” Leaked messages last week in a Tory MP WhatsApp group showed “red wall” MPs complaining that they would never be able to enact the Rwanda policy of deporting refugees if they did not leave the ECHR. In the messages reported by Sky News, Lee Anderson, MP for Ashfield, said the government’s promised legislation would “not stop the crossings”. And the Dudley North MP, Marco Longhi, said the ECHR “trumps everything and our own colleagues want to keep it even if it poses a security risk to UK people as we’ve just seen … We will be slaughtered at the locals and at the GE.” But others warned of a backlash. Sir Bob Neill, Tory chair of the Commons justice committee, told the FT: “If Conservatives don’t believe in the rule of law, what do we believe in? Are we going to put ourselves in the same company as Russia and Belarus?” Others who would be likely to baulk at the idea of leaving the convention include the development minister, Andrew Mitchell, and the former justice secretary Robert Buckland.