London: Surging inflation, ongoing strikes, health crises and war in Europe: the UK's incoming prime minister Rishi Sunak faces major challenges - as well as bitter rifts in the Conservative party.
Economic and social crises
Sunak's top priority is solving the economic crisis, with inflation exceeding 10 percent, the highest in any G7 country, owing to soaring energy tariffs and food prices.
Facing a looming threat of recession, Sunak has to calm the markets after they reacted with shock to a tax-cutting budget announcement by Liz Truss's government late last month.
Sunak will need to "reassure people that over the winter, there is not going to be widespread poverty and economic uncertainty", said Anand Menon, director of UK in a Changing Europe and professor of politics at King's College London.
As British people see inflation erode their spending power, train drivers and other sectors have already gone on strike this year.
For the first time in its 106-year history, the Royal College of Nursing is recommending industrial action by its members.
The National Health Service (NHS) "is on its knees", said Pippa Catterall, a professor of history and policy at the University of Westminster.
"There's a risk of hospitals not being able to cope," she added.
During his summer leadership campaign, Sunak called for measures to tackle inflation but "he was very short on details on how he's going to get inflation down", Catterall said.
Uniting the Tory party
After 12 years in power, the Conservative party is more divided than ever.
Boris Johnson resigned as leader in July after losing the confidence of some 60 ministers. Truss announced her resignation after just 44 days, never managing to command the respect of her MPs.
Sunak will become the fifth Tory prime minister since 2016 - following David Cameron, Theresa May, Johnson and Truss.
A majority of Tory MPs backed Sunak, seemingly giving him a solid mandate.
Nevertheless, within the party, "there's still the hard core of Boris fans", said Catterall. They see Sunak's role in the collapse of Johnson's government as a betrayal.
On Monday, Sunak reportedly warned Tory MPs they must "unite or die" as the opposition Labour Party soars in the polls, more than two years before the next general election is due.
Sunak, who backed splitting from the European Union in 2016, will now have to deal with the thorny issue of post-Brexit trade rules in Northern Ireland, which adjoins EU member the Republic of Ireland.
A draft bill currently going through parliament proposes scrapping parts of the deal. The EU warns this could spark retaliatory trade sanctions
Sunak has backed the bill.
But this will not be seen as enough by Northern Ireland's unionist parties, who have withdrawn from the power-sharing devolved government in Belfast over the issue.
Fresh elections need to be called in Northern Ireland unless the impasse is broken by October 28.
Since Brexit, Tory governments have issued unfulfilled promises to sharply cut immigration. This year, a record number of 37,570 people have crossed the Channel to England in small boats.
Sunak has backed a government plan to send asylum seekers who arrive in the UK illegally to Rwanda for processing. But the project has been blocked for months by legal action.
He has not yet made it clear what his stance will be on issuing more visas for workers needed to fill many blue-collar jobs in the UK.
The UK this year is providing military aid worth #2.3 billion ($2.6 billion) to Ukraine, more than any other country except the United States.
"I think nothing will change on Ukraine. I think there's a consensus not only in the Conservative party but across the two big parties about the need to take a firm stance on Russian aggression", said Menon.
As for China, Sunak has called it the "number-one threat" to domestic and global security.