LONDON - Former prime minister Boris Johnson on Saturday returned to Britain from a holiday to launch an audacious political comeback, as Conservative leadership rival Rishi Sunak reached the minimum threshold to contest the UK's top job.
Johnson cut short a Caribbean trip to join the seemingly three-person race to replace outgoing leader Liz Truss, with allies telling British media he was "up for it".
The divisive 58-year-old Brexit architect only relinquished power in early September, two months after announcing his resignation following a Tory revolt over a slew of scandals.
His apparent bid to return to office just weeks later has already been decried by opposition politicians, and even some in his own fractured ruling party who argue that both it and the country need stability and unity.
"We've got to go forward, not go back," Dominic Raab -- Johnson's deputy prime minister -- told Sky News, adding an imminent parliamentary inquiry into the "Partygate" scandal that dogged his former boss could prove too distracting.
Raab said former finance minister Sunak's economic experience meant he was the "standout candidate".
The Tories were forced into a second, this time expedited, leadership contest since the summer after Truss dramatically announced Thursday she would stand down -- just 44 tempestuous days into her tenure.
It followed a disastrous tax-slashing mini-budget that sparked economic and political turmoil which had been predicted by Sunak.
In a sign of the toll from the tumult, ratings agency Moody's said Friday it had downgraded Britain's outlook, blaming in part "heightened unpredictability in policy making".
Meanwhile, the pound -- which hit a record low against the dollar in the mini-budget's immediate aftermath, but had since rallied -- slumped.
'Fresh start'
Late Friday, Sunak's allies in parliament revealed he had garnered the nominations of 100 Conservative MPs, the threshold set by the party to stand.
However, both Sunak and Johnson are yet to announce they are running, with reports that a declaration by the former finance minister was imminent Saturday.
Cabinet member Penny Mordaunt, who just missed out on making the final runoff after Johnson quit, was the first to formally unveil her candidacy, on Friday.
The 49-year-old said she was running for "a fresh start, a united party and leadership in the national interest". But she is already trailing her rivals by dozens of nominations.
The accelerated contest will see the Conservatives' 357 MPs hold a vote Monday on any candidates with the 100 nominations, before a possible online ballot of party members later in the week if two remain.
The Sunak and Johnson camps are reportedly seeking talks to see if there is scope for a unity deal -- although there is plenty of bad blood since the former prime minister's defenestration.
Sunak's July resignation as chancellor of the exchequer helped trigger the government mutiny that ultimately led to Johnson's ousting.
James Duddridge, one of Johnson's closest allies in parliament, said late Friday he had been in contact with his old boss via WhatsApp.
"He said... I'm up for it," the MP told Sky News, hours before cameras captured Johnson disembarking a flight home from the Dominican Republic.
'Wielded the knife'
The ever-ebullient former leader has won the backing of several Tory heavyweights, including on Saturday ex-interior minister Priti Patel.
But in a sign of the party's divisions, some senior Tories, such as Johnson's former chief of staff Steve Barclay and his Brexit sherpa David Frost, warned against turning to him.
Ex-leader William Hague, Sunak's mentor, told Times Radio his return as prime minister would lead to a "death spiral" for the party.
Meanwhile veteran backbencher Roger Gale has warned that Johnson could face a wave of resignations from MPs refusing to serve under him again.
Although he remains popular with party members who could decide the contest, polling shows he remains broadly disliked by the electorate, with a YouGov survey finding 52 percent of voters opposed his comeback.
Another poll also found that three in five voters now want an early general election, in line with demands from opposition parties, as Britons struggle with a worsening cost-of-living crisis.
In Sunak's constituency in Yorkshire, northern England, 58-year-old farmer Elaine Stones said the party had made a mistake in electing Truss instead of him last month.
"He's honest, reliable and he should have been voted in last time," she told AFP.
"He wielded the knife and once you do that, you can't be trusted," she said.