Conservative divisions were laid bare on Tuesday as a wide-open field of eight MPs made it through to the first round of the fractious contest to succeed Boris Johnson as prime minister. Despite the 1922 Committee setting a threshold of 20 MPs to secure a place on the ballot paper, just three of the 11 declared candidates were eliminated on a frenetic day in Westminster. Rishi Sunak is the frontrunner among MPs by some margin, with the publicly declared support of more than 40 colleagues, but it remains unclear who will join him in the final two. Conservative MPs will vote on Wednesday, with any contender attracting fewer than 30 votes eliminated. Further rounds will follow until the field is narrowed to two, with Conservative members then making the final decision. Sajid Javid, whose resignation helped precipitate Johnson’s demise, dropped out of the race shortly before the formal announcement of the candidates by 1922 Committee chair, Graham Brady, on Tuesday evening. The former health secretary did not immediately endorse any of his rivals. Brady said eight candidates had met the threshold to proceed: Kemi Badenoch, Suella Braverman, Jeremy Hunt, Penny Mordaunt, Sunak, Liz Truss, Tom Tugendhat and Nadhim Zahawi. Sunak, whose resignation alongside Javid set off the mass walkout that led to Johnson’s downfall, is a controversial figure in his party despite his staunch backing from MPs, and is blamed by many Tories for the rapid increase in the tax burden on his watch. The culture secretary, Nadine Dorries, who announced her support for Liz Truss on Tuesday morning, claimed “dirty tricks/a stitch up/dark arts” had helped get Hunt into the next round. “Team Rishi want the candidate they know they can definitely beat in the final two and that is Jeremy Hunt,” she tweeted. Sunak’s team flatly denied urging some of his supporters to lend their votes to Hunt to help him over the line. A source in Hunt’s team said: “This is categorically untrue and we hope all candidates and supporters will campaign on their own merits rather than attempting to smear opponents.” Earlier, three candidates – Badenoch, Sunak and Tugendhat – held simultaneous launch events. Tugendhat, considered to be a centrist, was introduced by his highest-profile backer, Anne-Marie Trevelyan, the trade secretary. He said his leadership would rise to the challenges of the cost of living crisis in a way his cabinet rivals had not. “In a moment that is so desperate for so many – and when our service is most needed – we have retreated,” he said. “We have retreated into division when we desperately need unity. When our nation needed our party to function, we retreated into faction. When the moment demanded service, we delivered scandal.” Badenoch was watched at her event by Michael Gove, sacked as communities secretary by Johnson last week as he fought to save his premiership. In an energetic speech in front of union flags that earned her a standing ovation from a packed room at the Policy Exchange thinktank, Badenoch criticised the “betrayal” of rivals’ tax cut pledges, which she said they would not keep. She said she would not enter into a bidding war with MPs who claim “my tax cut is bigger than yours” but she was committed to reducing taxes on businesses, families and individuals. Mordaunt and Truss are expected to launch their campaigns soon, with both vying to be the “stop Rishi” candidate who could win over the party membership. Throughout the day the backers of contenders who had not yet met the threshold of 20 supporters frantically tried to win around their colleagues. The home secretary, Priti Patel, announced just before 2pm that she would not be standing. There had been rumours that she might strike a deal with her fellow Brexiter Braverman, but Patel declined to publicly back any other candidate. “Like all Conservative MPs and party members, I will be listening to cases being put forward by the candidates standing for the leadership of the party and trust the contest will be conducted in a good spirit that brings our party together,” she said in a statement. Rehman Chishti, the little-known backbencher who had launched a quixotic leadership bid despite having no declared supporters, withdrew. Sunak was introduced at his launch by the deputy prime minister, Dominic Raab. Raab said the former chancellor was “a true Conservative, imbued with the values of enterprise, hard work and family. Rishi’s values are our values.” Grant Shapps, the transport secretary, also attended Sunak’s slickly managed event, having folded his own campaign as it became clear he was unlikely to secure 20 backers. Other senior supporters present including Oliver Dowden, who resigned as party chair after the disastrous byelections in Tiverton and Honiton and Wakefield, and the former international trade secretary Liam Fox. Sunak had no new policies to announce, saying he wanted to have a “grownup conversation” with the public instead of making lavish promises of tax cuts, as some of his rivals have done. With some MPs claiming he has been disloyally plotting against Johnson, he paid tribute to the outgoing prime minister, saying: “Boris Johnson is one of the most remarkable people I’ve ever met, and whatever the commentators say, he has a good heart.” He denied that Johnson’s controversial former chief of staff Dominic Cummings had any involvement in his campaign, or would be handed a role in “any government I have the privilege to lead”. Shortly before Sunak’s launch, Dorries made a statement alongside the Brexit opportunities minister, Jacob Rees-Mogg, in which they both said they would support Truss. “She’s probably a stronger Brexiter than both of us; she has consistently argued for low tax policies,” said Dorries, adding that it was important to ensure the 2019 Tory manifesto was enacted. Rees-Mogg highlighted the fact that Truss had argued in cabinet against “Rishi’s tax rises”.