Rebel Tory MPs are betting that Boris Johnson will “blow himself up” with further scandals over the summer so that the rules protecting him from another confidence vote can be changed to force him from office. The prime minister narrowly survived a ballot on his premiership this week, helped partly by potential leadership contenders deciding to hold off launching their own campaigns. Under Conservative party rules, Johnson is immune from another vote for 12 months. But the Guardian understands that the 1922 Committee, which oversees such votes, could cut that period to six months, or even less. Elections to the committee’s executive are expected to take place in the coming weeks and will be viewed by some as a de facto vote on whether to take such a step. Given that the committee’s officers are made up mostly of MPs who are believed to want Johnson gone – including Graham Brady, William Wragg, Nusrat Ghani and Geoffrey Clifton-Brown – rebels said their re-election would be likely to mean Johnson could face another confidence vote before next June. The executive is able to change the rules regarding such contests by a majority vote and does not require the support of the whole parliamentary party. Tory rebels admitted they had “pressed the nuclear button” with Monday’s vote and been left with few further options to help them pile pressure on Johnson. Plans are being drawn up for a “vote strike” to paralyse the government’s legislative agenda if necessary. But many are confident Johnson will “blow himself up” with further scandals, providing the impetus for another confidence vote in the autumn. They pointed to a string of embarrassments for the prime minister – such as the standards row over protecting the disgraced former MP Owen Paterson, an undeclared loan for redecoration of Johnson’s Downing Street flat, and Partygate – and believe further “unforced errors” are likely. A bullish Johnson on Wednesday brushed off the embarrassment of 41% of his MPs declaring they had no confidence in him in Monday’s private ballot. He said his premiership had “barely begun” and claimed he had “picked up political opponents all over the place” because the government was achieving “some very big and very remarkable things”. He said during prime minister’s questions: “Absolutely nothing and no one … is going to stop us from getting on with delivering for the British people.” But he received fresh criticism from a Tory peer, who was then forced to step down as a government adviser. Helena Morrissey, a staunch Brexiter, said the prime minister being booed at a platinum jubilee event last weekend suggested he had “become a liability rather than an asset”. Asked if Johnson should carry on, Lady Morrissey told LBC: “In all honesty, I would rather he didn’t.” She said he was “in the wrong job”, had shown no contrition and should “go with dignity”. After the intervention, Morrissey, who was made a peer by Johnson in September 2020, was told to quit her role on the board at the Foreign Office and did so. A former No 10 adviser said it was a “mistake for the PM to be demob happy” because once someone had rebelled and “crossed the Rubicon” to vote against him, it would be hard to get them back. But they said potential leadership contenders such as Penny Mordaunt, Jeremy Hunt and Tom Tugendhat were likely to stay quiet for now. Other cabinet ministers thought to be eyeing up the top job but who have stayed loyal include Liz Truss, the foreign secretary, and Nadhim Zahawi, the education secretary. The former adviser said: “No one is willing to solve the collective problem of a leadership race, which requires multiple people to take the jump individually.” Government sources played down the threat of an immediate cabinet reshuffle, suggesting No 10 was nervous about creating more enemies by demoting ministers. With many Tories “pricing in” expected defeat in two byelections on 23 June – in Wakefield to Labour and in Tiverton and Honiton to the Liberal Democrats – the sources suggested Johnson would want to wait until after those contests before launching another government reset.