The woman widely expected to be elected prime minister of the United Kingdom, Elizabeth Truss, said Sunday that tackling the country’s growing energy crisis will be near the top of her agenda when she officially takes over later this week.

Speaking to the BBC, Ms. Truss — the United Kingdom’s Foreign Secretary — declined to offer any details on her plan, but reports in the British media suggest that she is prepared to spend as much as 100 billion pounds to offset cost-of-living increases fueled by soaring energy prices in Britain and across Europe.

“I want to reassure people that I am absolutely determined to sort out this issue as well as, within a month, present a full plan for how we are going to reduce taxes, how we’re going to get the British economy going, and how we are going to find our way out of these difficult times,’’ Ms. Truss told the BBC.

Members of Ms. Truss’ Conservative Party have been bogged down for weeks by a bitter battle between her and former finance minister Rishi Sunak for the top Tory spot. The winner of the election, in which 180,000 party members voted, will be announced Monday.

Following the announcement, the victor will meet with Queen Elizabeth at Balmoral Castle in Scotland and be asked to form a new government to replace the one led by outgoing Prime Minister Boris Johnson for the past three years.

Britain, like much of Europe, has been wracked by soaring energy prices caused by the conflict in Ukraine and the continent’s dependence on Russian supplies. Analysts have warned that household energy bills could jump by 80 percent next month, possibly leaving one in three Britons in danger of being unable to afford to heat their homes this winter.

Adding to the general malaise in England is sky-high inflation, repeated strikes by rail workers and other industrial unions, long waiting lists for the country’s National Health Service, and rumblings about another bid for independence by Scotland.

During her campaign, Ms. Truss promised to cut taxes and increase the supply of energy — as well as boost military spending — but offered few details about how she would do it.

In an article published in Sunday’s Telegraph newspaper, Ms. Truss said she understood the pain being felt by her fellow Britons and pledged to take “decisive action to ensure families and businesses can get through this winter and the next.”

She said she would appoint a Council of Economic Advisers to get “the best ideas” for the economy.

“We need to take the difficult decisions to ensure we are not in this position every autumn and winter,” she said. “Sticking plasters and kicking the can down the road will not do. I am ready to take the tough decisions to rebuild our economy.”

Ms. Truss’ elevation to 10 Downing Street comes in good part on the back of her strident support for Britain’s withdrawal from the European Union during the campaign. As foreign secretary, she sparred with European leaders over post-Brexit trade agreements related to Northern Ireland that officials in Washington worry could spark a trade war between London and Brussels.

In her quest to carry on Mr. Johnson’s vision of a more activist Britain on the global stage, Ms. Truss also is likely to continue her predecessor’s embrace of Ukrainian President Zelensky and hawkish tone toward Russia.

She has shown less regard, however, for the so-called “special relationship” between the United States and Great Britain, suggesting at a party conference last year that it was “special, but not exclusive,” and rattling off all of England’s other allies such as Australia, India, and Europe’s major players.

Britain should not, she said at the conference, preen for the United States “like some teenage girl at a party if we’re not considered to be good enough.”