On the day the Bank of England warned that Britain was facing a long-term downturn, Liz Truss claimed that she could prevent a recession if she became prime minister.
The BoE's projected downturn could be averted if she wins the contest, as she promised immediate tax cuts if she is elected.
She said during the event in which she sparred with her rival that it was not inevitable. The economy can be changed to make it more likely to grow.
The former chancellor, Sunak, had planned to raise corporation tax from 19 to 25 per cent.
Sunak said that Truss's plans would cause inflation to go up. He said that the Conservatives needed to get real and fast. Inflation is the root cause of the economy's flashing lights.
He admitted that his refusal to offer tens of billions of pounds of tax cuts was costing him politically, but he was worried that Liz Truss's plans would make the situation worse
Some in the party think that the foreign secretary has a lead of 30 points or more. The audience of Tories on a show of hands favored Sunak over Truss after the debate.
There were calls for an increased windfall tax on energy companies, but the foreign secretary turned them down.
She said she would do more to help people if there was more money.
He defended his decision to resign from Boris Johnson's cabinet, saying he was not prepared to defend the prime minister's lies in relation to the Chris Pincher sexual harassment case.
The darkening economic outlook is dominating the leadership contest and Sunak hopes he still has time to convince the membership that he is the right candidate.
The former chancellor has time to try to retrieve the situation, as only one member of the audience got a ballot paper.
The BoE predicted that inflation would hit 13 per cent by the end of the year after raising interest rates sharply.
The Monetary Policy Committee voted to raise interest rates by half a percentage point on Thursday, the largest increase in 27 years.
The country will slide into a 15-month recession later this year, according to the bank's predictions. According to Consensus Economics, the US will grow by 1.5 per cent and the eurozone by 1.7 per cent in the next five years.
The BoE predicted that inflation would rise to 13 per cent at the end of the year because of the surge in gas prices. It would fall back to the 2 percent target in two years.