Rishi Sunak and Boris Johnson have engaged in an extraordinary war of words over the former prime minister’s failed attempts to elevate several close allies to the House of Lords. The prime minister accused his predecessor on Monday morning of having lobbied him to overturn due process and appoint three Conservative MPs to the House of Lords – claims Johnson dismissed publicly as “rubbish”. The exchanges brought into the open the long-running dispute between the two men, which has caused a wider rift in the Conservative party and triggered a series of byelections that could test Sunak’s grip on power. The public row began on Monday morning, three days after Downing Street published Johnson’s resignation honours list without the names of three MPs whom the former prime minister wanted to make peers – Nadine Dorries, Nigel Adams and Alok Sharma. Asked about the controversy during a speech at London Tech Week, Sunak defended the decision not to include those names, given that the House of Lords Appointments Commission (Holac) recommends that any MP recommended for a peerage should stand down to take up the new position within six months. “Boris Johnson asked me to do something that I wasn’t prepared to do, because I didn’t think it was right. That was either overrule the Holac committee, or make promises to people,” he said. “Now, I wasn’t prepared to do that, so I didn’t think he was right. And if people don’t like that then tough.” Johnson hit back within hours, issuing a statement saying: “Rishi Sunak is talking rubbish. To honour these peerages it was not necessary to overrule Holac – but simply to ask them to renew their vetting, which was a mere formality.” Johnson’s allies have never forgiven Sunak for his decision to stand down as chancellor last year, a move that helped bring down Johnson as prime minister. Tensions were renewed over recent weeks over both Johnson’s honours list and the decision by the Cabinet Office to withhold some of the former prime minister’s communications from the Covid-19 inquiry. Johnson unexpectedly announced on Friday he would resign as an MP immediately after learning that the House of Commons privileges committee was set to recommend he be suspended for at least 10 days for lying to the house about Partygate. Dorries and Adams also resigned, setting up three difficult byelections for the Conservatives within the next few months. Dorries told the Times on Monday she believed Downing Street had “withheld information”, leading her to believe incorrectly that she would be given a peerage Sunak’s allies toured the broadcasting studios on Sunday and Monday trying to draw a line under the affair, with both Grant Shapps, the energy secretary, and Michael Gove, the communities secretary, suggesting it was time to move on from the drama of the Johnson years. Sunak’s official spokesperson said on Monday it was “entirely untrue” that the prime minister or his No 10 team removed names from Johnson’s peerages list. Downing Street received the final list from Holac, which confirmed at the weekend it had rejected eight of the proposed peerages, in February. Since then, the government has been waiting for the Cabinet Office to finish vetting names put forward for other honours. Initially, the delay was attributed to the large number of honours Johnson wanted to bestow on his close friends and confidants, reportedly including a knighthood for his father, Stanley. Downing Street also defended the work of MPs on the privileges committee, which has been the focus of attacks by Johnson and his allies. Sunak’s official spokesperson said: “This is a properly set-up committee that the house has voted to carry out their work. The government will in no way traduce or criticise the work of the committee who are doing exactly what parliament has asked them to do.” Asked about reports that committee members had been offered security as a result of the attacks, the spokesperson added: “Clearly, any threats against any MPs are completely unacceptable.” Some of Johnson’s parliamentary allies rallied to his cause later in the day, with Jake Berry, the Tory backbencher, telling reporters on Monday: “The establishment has seen Boris out the door.” However, a wider rebellion by Johnson supporters seemed to have been averted, with little sign that Sharma or others were prepared to resign their seats in protest at Downing Street.