Could Boris Johnson Make a Comeback as U.K. Prime Minister?

LONDON — It seemed at once incredible and inevitable.

No sooner had Prime Minister Liz Truss of Britain announced her sudden resignation on Thursday afternoon than a familiar name surfaced as a candidate to succeed her: Boris Johnson, the prime minister she replaced a mere 45 days ago.

Mr. Johnson, who is vacationing in the Caribbean, has said nothing publicly about a bid for his old job. But the prospect of Boris redux has riveted Conservative Party lawmakers and cabinet ministers — delighting some, repelling others, and dominating the conversation in a way that Mr. Johnson has for his entire political career.

Nor is the idea of his return merely notional: Among those who are keeping tallies of the voting intentions of lawmakers, including some London news organizations, Mr. Johnson is only slightly behind his chief rival, Rishi Sunak. On Friday morning, Jacob Rees-Mogg, who is currently the business secretary and served under Mr. Johnson, became the first cabinet minister to endorse his former boss.

But the prospect of Mr. Johnson back in 10 Downing Street appalls many Conservatives, who cite the serial scandals that brought him down in July and argue that voters would never forgive the party for rehabilitating him. Embracing such a polarizing figure, they say, would splinter the Tory ranks, perhaps irrevocably.

“Only a nation which was gripped by pessimistic despair and no longer believed that there could be a serious response to its unfolding tragedies would want to take refuge in the leadership of a clown,” Rory Stewart, who ran unsuccessfully against Mr. Johnson in 2019, wrote on Friday on Twitter.

And yet, as Mr. Johnson’s supporters never tire of pointing out, he delivered a landslide Conservative victory in the general election of 2019. After the calamitous tenure of Ms. Truss, in which she tried to engineer a radical economic agenda with the support of only a third of the Tories in Parliament, some say that mandate gives him — and him alone — the capacity to restore the party’s depleted electoral fortunes.

“One person was elected by the British public with a manifesto and a mandate until January ‘25,” Nadine Dorries, a former cabinet minister who is one of Mr. Johnson’s most outspoken backers, wrote on Thursday on Twitter.

Under election rules laid out by the party on Thursday, candidates need 100 nominations from lawmakers to appear on the ballot next week. According to the informal tallies, neither Mr. Johnson nor Mr. Sunak is close yet, though in one spreadsheet, which includes unnamed supporters, Mr. Johnson is at 52.

Setting a threshold of 100 nominations was intended to winnow the field to a handful of candidates and keep the race brief, thus avoiding the drawn-out, divisive campaign that was won by Ms. Truss. Given that there are only 357 Conservative lawmakers, there can be, at most, three names.

There is a lively debate in political circles about whether Mr. Johnson can clear that hurdle, but with several more lawmakers coming out in his favor on Friday, it no longer seems implausible. Asked who was likely to be the next prime minister, a member of the government texted in reply, “Boris?”

Andrew Gimson, who wrote a biography of Mr. Johnson, said, “I think he’s got a very good chance of coming back. He’s got real momentum.” For a demoralized party trailing in the polls, Mr. Gimson said, “It would be a much better story if Boris came back. There would be a sense of incredulity — the sheer spectacle of it.”

If Mr. Johnson were to emerge from the ballot as one of two surviving candidates, the odds of his winning could rise considerably. The choice would then go to the party’s 160,000 or so members, among whom Mr. Johnson remains enduringly popular. Mr. Sunak, whose resignation as chancellor of the Exchequer in July helped set in motion Mr. Johnson’s downfall, is viewed with suspicion by many party members, even if he has solid support among the lawmakers.

That is why some political analysts expect the party’s elders to lean on the candidate with fewer votes to withdraw before that stage.

There are other significant hurdles to Mr. Johnson’s return: He is under investigation by a parliamentary committee over whether he misled the House of Commons about parties held in Downing Street that broke pandemic rules. It could recommend Mr. Johnson’s expulsion or suspension from Parliament.

For all of his charisma, it is also not clear that Mr. Johnson retains the same power to turn out voters that he did three years ago. The scandals that brought him down eroded his popularity with many Britons, and it was under his watch that the polls began to tilt heavily toward the opposition Labour Party.

Finally, there is the question of whether Mr. Johnson is actually ready to return. In his farewell speech to Parliament, he signed off with, “Hasta la vista, baby,” Arnold Schwarzenegger’s famous line from the movie “Terminator 2.” He later compared himself to Cincinnatus, a fifth-century Roman politician who saved the state from an invasion, retired to his farm, then subsequently returned to Rome as leader.

Still, as a highly visible former prime minister, Mr. Johnson is in line to take in millions of dollars on the after-dinner speaking circuit. He is expected to write another newspaper column, a gig that could bring him several hundred thousand pounds a year.

Mr. Johnson could also receive a lucrative advance for his memoirs, though that is complicated by the fact that he already owes the Hachette Book Group a biography of Shakespeare. Publishing executives said that if he sold the memoir to Hachette, it could allow him to set aside the Shakespeare book.

With two young children with his wife, Carrie, and several other children by his former wife, Marina, people who know Mr. Johnson say he is keen to make big money — something he cannot do as a serving prime minister, even if the job comes with housing and a comfortable salary of £164,080, or about $182,400.