Liz Truss became U.K. prime minister on Tuesday and immediately confronted the enormous task ahead of her amid increasing pressure to curb soaring prices, ease labor unrest and fix a health care system burdened by long waiting lists and staff shortages.

At the top of her in-box is the energy crisis triggered by Russia's invasion of Ukraine, which threatens to push energy bills to unaffordable levels, shuttering businesses and leaving the nation's poorest people shivering in icy homes this winter.

Truss, who refused to spell out her energy strategy during the two-month campaign to succeed Boris Johnson, now plans to cap energy bills at a cost to taxpayers of as much as 100 billion pounds ($116 billion), British news media reported Tuesday. She is expected to unveil her plan on Thursday.

"You must know about the cost of living crisis in England, which is really quite bad at the moment," Rebecca Macdougal, 55, who works in law enforcement, said outside the Houses of Parliament.

"She's making promises for that, as she says she's going to deliver, deliver, deliver," she said. "But we will see in, hopefully, the next few weeks there'll be some announcements which will help the normal working person."

Truss took office Tuesday afternoon at Balmoral Castle in Scotland, when Queen Elizabeth II formally asked her to form a new government in a carefully choreographed ceremony dictated by centuries of tradition. Johnson, who announced his intention to step down two months ago, formally resigned during his own audience with the queen a short time earlier.

It was the first time in the queen's 70-year reign that the handover of power took place at Balmoral, rather than at Buckingham Palace in London. The ceremony was moved to Scotland to provide certainty about the schedule because the 96-year-old queen has experienced problems getting around that have forced palace officials to make decisions about her travel on a day-to-day basis.

Truss, 47, took office a day after the ruling Conservative Party chose her as its leader in an election where the party's 172,000 dues-paying members were the only voters. As party leader, Truss automatically became prime minister without the need for a general election because the Conservatives still have a majority in the House of Commons.

But as a prime minister selected by less than 0.5% of British adults, Truss is under pressure to show quick results.

Ed Davey, leader of the opposition Liberal Democrats, on Tuesday called for an early election in October.

"I've listened to Liz Truss during the Tory leadership (campaign) and I was looking for a plan to help people with their skyrocketing energy bills, with the NHS crisis and so on, and I heard no plan at all," he told the BBC.

"Given people are really worried, given people are losing sleep over their energy bills, businesses aren't investing because of the crisis, I think that's really wrong," Davey said.

Johnson took note of the strains facing Britain as he left the prime minister's official residence at No. 10 Downing Street for the last time, saying his policies had left the government with the economic strength to help people weather the energy crisis.

While many observers expect Johnson to attempt a political comeback, he backed Truss and compared himself to Cincinnatus, the Roman dictator who relinquished power and returned to his farm to live in peace.

"Like Cincinnatus, I am returning to my plow," he said. "And I will be offering this government nothing but the most fervent support."