British Prime Minister Boris in London, Britain, June 22, 2022. (REUTERS)

Top conservative figures are urging Boris Johnson to resign following his historic double by-election defeat, as rebellious MPs plot new ways to depose him.

Former Conservative leader Michael Howard was among those who demanded that the prime minister step down following the losses in Tiverton, Honiton, and Wakefield, which prompted the party's co-chair, Oliver Dowden, to resign immediately.

Dowden told the prime minister in his pointed resignation letter, widely regarded as a call to others to act, “We cannot carry on with business as usual. Someone must take responsibility.”

Johnson's detractors are hoping to gain a majority on the executive of the influential 1922 Committee of Tory backbenchers in order to change the party's rules to allow a fresh confidence vote without having to wait a year.

As the magnitude of the twin defeats became clear – both with larger-than-expected swings against the Conservatives – a number of senior Conservatives joined those calling for Johnson's resignation. When asked if the prime minister should resign, Howard replied, "I do."

“The party and more importantly the country would be better off under new leadership,” he added. “Members of the cabinet should very carefully consider their positions. It may be necessary for the executive of the 1922 Committee to meet and to decide to change the rules so another leadership election could take place.”

Former Foreign Secretary Malcolm Rifkind suggested that disgruntled ministers would work together to persuade Johnson to resign.

“I think it is hugely in the public interest that preferably the prime minister seeks their views. If he’s not willing to see their views because you might be rather worried of what they might say to him, then they must, at least in some number, come together and go and see him,” he said.

At a press conference in Kigali, Rwanda, where he is attending the Commonwealth Heads of Government summit, Johnson struck a defensive tone, refusing to admit anything about his own behavior was to blame for the byelection debacle.

He has been grappling with calls to resign after a series of leaks showed that several social gatherings were held at his offices throughout 2020 and 2021, flouting Covid-19 social distancing rules, which later became known as the Partygate scandal. The scandal gravely affected his party's standing.

See more: Most of the British public wants Boris Johnson to resign