Foreign Secretary Liz Truss promised to cut taxes as soon as she took office, using borrowing to pay for it. Former Treasury chief Rishi Sunak said he would get inflation under control first, arguing that Truss’s plan would increase the public debt and leave people worse off in the long run.

Tempers flared as Sunak said that “it’s not moral to ask our children to pick up the tab for the bills that we’re not prepared to pay.”

Truss called that “Project Fear” and said it was sensible to borrow to rebuild from the coronavirus pandemic, a “once in a 100-year event.”

The pair are battling to succeed Boris Johnson, who quit as leader of the governing Conservative Party on July 7 after months of ethics scandals triggered a mass exodus of ministers from his government. The contest has exposed deep divisions within the party as it tries to move on from the tarnished, but election-winning Johnson.

Oddsmakers say Truss is the favorite to win. She outperforms Sunak in polls of Conservative members — though Sunak has the edge among voters as a whole.

The winner will be chosen by about 180,000 Conservative Party members and will automatically become prime minister, governing a country of 67 million. Party members will vote over the summer, with the result announced Sept. 5. Johnson remains caretaker prime minister until his successor is chosen.

Truss, 46, and Sunak, 42, have wooed Conservatives by doubling down on policies thought to appeal to the right-wing Tory grassroots, including a controversial plan to deport some asylum-seekers to Rwanda.

The government says the policy will deter people-traffickers from sending migrants on hazardous journeys across the Channel. Political opponents, human rights organizations and even a few Conservative lawmakers say it is immoral, illegal and a waste of taxpayers’ money.

The first scheduled deportation flight was grounded after legal rulings last month, and the whole policy is now being challenged in the British courts.

Hard-line policies like the Rwanda plan are less popular with voters as a whole than with Conservatives, but the British electorate won’t get a say on the government until the next national election, due by the end of 2024.

The leadership election is taking place during a cost-of-living crisis driven by soaring food and energy prices, partly due to the war in Ukraine. While many countries are experiencing economic turbulence, in Britain it’s compounded by the country’s departure from the European Union, which has complicated travel and business relations with the U.K.’s biggest trading partner.

Both Sunak and Truss are strong supporters of Brexit, which was the signature policy of the Johnson government.

Both denied Brexit was responsible for huge queues of vehicles waiting to cross to France at the port of Dover in recent days.

Sunak is running as the candidate of fiscal probity, while Truss has positioned herself as a disruptor who will “challenge orthodoxy” and “get things done.”

The two sparred on topics such as policy toward China, with Truss accusing Sunak of changing his stance on relations with Beijing.

Sunak says that China represents the “biggest-long term threat to Britain” and that if elected he would close the 30 Confucius Institutes in Britain. Funded by the Chinese government, the institutes teach Chinese language and culture, but have been accused of spreading pro-Beijing propaganda.

“As recently as a month ago you were pushing for closer trade relationships with China,” said Truss, who warned the West must not become “strategically dependent” on China.

“I’m delighted that you’ve come round to my way of thinking,” she said.

Sunak faces hostility from allies of Johnson, who consider him a turncoat for quitting the government earlier this month, a move that helped bring down the prime minister. Truss chose to remain in the caretaker government.

Both candidates, though, said Johnson would not be part of their government if they became prime minister.

“I think we need to look forward at this point,” Sunak said.

Truss said Johnson “deserves a well-earned break, and added: “What’s done is done.”

Many Conservatives worry that the bitter internal fighting the campaign has already brought is only benefitting the opposition Labour Party. Former party chairwoman Amanda Milling said the contest was “more toxic than I’ve ever seen.”

Writing on Twitter, she urged both candidates to sign up to a “Clean Campaign Charter,” saying that without it “the lasting damage to our Party could see us out of power for a decade.”