LONDON — Rarely free from scandal and never out of the headlines as Britain’s charismatic prime minister, Boris Johnson dominated British politics, overshadowed his rivals and reinvented his governing Conservative Party in his own compelling, polarizing image.
So for all the acrimony his leadership brought with it, Mr. Johnson’s departure leaves a gaping void in the stewardship of a country charting a troubled post-Brexit future and a dire economic backdrop.
Despite Mr. Johnson’s missteps, there is no prospect of an imminent general election under Britain’s parliamentary system, leaving the ultimate choice of Britain’s next leader to the roughly 200,000 members of the Conservative Party.
The political crisis is far from over for Britons weary of Mr. Johnson’s nonstop dramas, anxious about spiking inflation and a possible recession, and in the dark about where the next prime minister will lead them.
“There is an opportunity for the Conservative Party to regain its footing with renewal and a honeymoon,” said Matthew Goodwin, a professor of politics at Kent University. “But the policy offering is going to have to be very different — they are going to have to offer a very different zeitgeist, and do so quickly, because the Conservative brand is associated with Johnson and is not in a good place.”
He added, however, that the Conservative Party “has always reinvented itself: It did it through Johnson, and now the contenders to succeed him have to set out a convincing case for why they meet this moment of reinvention.”
That will mean answering fundamental questions about the type of country they want to build, including many that were never addressed because of the fallout from the 2016 Brexit vote and the pandemic.
Jill Rutter, a former civil servant and a senior fellow at the Institute for Government, a London-based research group, also predicted “a battle over direction,” citing debates over Brexit, taxation and the economy.
“The real question is: Are they capable of putting a team back together in the longer term without Boris Johnson?” she asked, adding that many of those in the more prominent positions in the government were appointed, primarily, for loyalty to their leader.
There will be no shortage of candidates: The number of lawmakers putting their names forward is likely to reach double figures. Some will run to raise their profiles, and a series of ballots among Conservative lawmakers will whittle the real contenders down to two.
One of them will then be chosen as the country’s next prime minister by members of the Conservative Party around the end of the summer, though questions swirled on Thursday about whether Mr. Johnson should be allowed to remain as caretaker prime minister until then.
Leading contenders to fill the job include Nadhim Zahawi, the recently appointed chancellor of the Exchequer; Rishi Sunak, his predecessor; Liz Truss, the foreign secretary; Ben Wallace, the defense secretary; and Jeremy Hunt, the former health and foreign secretary.
Ms. Rutter said that, before Mr. Johnson’s resignation, there was a mind-set that Conservatives would likely have two years until an election, which would have given the party time to effectively resolve the outstanding aspects of Brexit, “get the economy back on track and restore a bit of faith” in the leadership. Now those challenges are more urgent.
Yet after three years in Downing Street, Mr. Johnson leaves an ideologically confused legacy, presenting successors with a challenge to unite their fractious party.
Mr. Johnson won a landslide election in 2019 promising to “get Brexit done” after three years of gridlock over how — or whether — to proceed with Britain’s exit from the European Union.
With his populist pro-Brexit message, Mr. Johnson managed to realign British politics, winning over millions of voters from the Labour Party in so-called “red wall” former industrial regions in the north and middle of Britain. He also promised to “level up” prosperity to those areas, sometimes to the alarm of traditional Conservative voters in the south who thought they might lose out.
Labour is still trying to recover in northern seats where support for Brexit was strong and where its left-wing previous leader, Jeremy Corbyn, proved unpopular. The current leader, Keir Starmer, is widely regarded as competent but uncharismatic, and has made solid but unspectacular progress.
That could be thrown off course if Mr. Starmer is fined by the police for breaking lockdown rules, however. Under such circumstances he has promised to quit, something that would precipitate a Labour leadership contest.
“The extraordinary thing is that by the end of next week we could have no leader of the Conservative Party and no leader of the Labour Party,” said Peter Lilley, a Conservative member of the House of Lords and a former cabinet minister.
Yet the contest inside the Conservative Party is the more pressing and important one, as it will determine the next prime minister.
Although the Tories see themselves as committed to reducing taxes, the burden of taxation soared as public services were strained during the pandemic. Mr. Johnson, always a fan of big infrastructure projects, often favored public spending and described himself as a “Brexity Hezza” — a reference to the interventionist (but pro-European) Conservative politician Michael Heseltine, who served in cabinet in the 1980s and 1990s.
The Fall of Boris Johnson, Explained
Yet the free-spending model was anathema to Brexit hard-liners, who thought the party had lost its ideological moorings and saw Britain’s departure from the European Union as the prelude to a major reduction in the role of the state, a concept nicknamed Singapore-on-Thames.
“There is going to be a long slate of candidates and they will have to set out their vision of post-Brexit conservatism, which is very different to pre-Brexit conservatism, of how they will take with them the working-class red wall areas along with the graduate, middle-class shires,” said Professor Goodwin.
The candidates would have to describe their vision of Britain’s post-Brexit trading plans, cultural issues and progressivism, immigration and the economy, he said, adding that, for now, there is no compelling set of ideas.
Tobias Ellwood, a senior Conservative lawmaker and critic of Mr. Johnson, said his colleagues were divided roughly into three groups: lawmakers from “red wall” seats who entered Parliament in 2019; moderate, more internationalist lawmakers known as the One Nation group; and hard-line Brexit supporters.
“Whoever can sit in the middle and then attract support from all three groups will become the prime minister,” Mr. Ellwood said.
Mr. Lilley, who ran for the party leadership in the 1990s, said that because the final choice is made by party activists, who tend to be more ideological than the general public, “the more right wing of the two wins.”
In this case, he said, that would favor a candidate who wanted to cut taxes and continue Mr. Johnson’s hard-line policy on changing post-Brexit trading rules for Northern Ireland without E.U. agreement.
But Professor Goodwin said that to salvage their party’s fortunes, contenders to be the next prime minister would have to produce a broader vision for modern Britain and a more thoughtful policy program than simply offering tax cuts.
The Conservative Party, he added, “is in a very fragile position and this will either go well, or very, very badly.”