The race to succeed Boris Johnson and lead Britain's Conservative Party to become the country's next prime minister is down to the wire, with both candidates clashing in a sometimes fiery debate, Monday night.

The last two candidates standing are the country's foreign secretary, Liz Truss and Rishi Sunak, the former Treasury chief who resigned from Boris Johnson's government last month. 

The contest has primarily revolved around taxes and the economy in the post-COVID world, as well as immigration and navigating the waters of the post-Brexit era. 

During Monday's televised debate Sunak had the most to prove, but it was Truss who pounced on his record by stating, "Rishi, you've just put in the highest tax rises for 70 years. How on earth can you claim that's going to lead to economic growth, and where have the growth policies been for the last two-and-a-half years?"

Photo combo of Liz Truss and Rishi Sunak

This combo of file photos shows the remaining candidates in the Conservative Party leadership race, former Chancellor of the Exchequer Rishi Sunak and Foreign Secretary Liz Truss. (AP Photo, File)

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Sunak defended his position and stated, "Let fiscal responsibility slide... it will lead us straight into penury." Inflation and the high cost of living have also been at the forefront of the candidate's agendas. 

Sunak said that the country needed to get a "grip of inflation," warning that if that wasn't done now mortgage rates would rise to 7%. He also said millions of people will be sent into poverty and that will mean the Conservative Party won't have a chance of winning the next election. 

Truss, who is leading in the polls, wanted to know why he would support raising taxes during this economic slow down. Truss outperformed her rival, said Nile Gardiner, Director of the Heritage Foundation’s Margaret Thatcher Center for Freedom. 

"Rishi Sunak, being the former Chancellor, looked overly eager and overly aggressive, constantly interrupting and this was not a good look for Mr. Sunak," Gardiner said.

Britain's Secretary of State for Foreign, Commonwealth and Development Affairs, Liz Truss receives applause

Britain's Secretary of State for Foreign, Commonwealth and Development Affairs, Liz Truss receives applause from her team near Parliament in London, Wednesday, July 20, 2022.  (AP Photo/Frank Augstein)

Sunak interrupted Truss 22 times within the first 12 minutes of the debate, leading to criticism by Conservative party members, and showed perhaps why he is trailing to Truss. 

Gardiner continued, "He comes across as someone who is in an increasingly desperate position and the debate certainly reflected that… this was a calm and commanding performance from Liz Truss." 

During campaigning both Sunak and Truss have claimed to be former Prime Minister Margaret Thatcher’s heir, but Gardiner said that title only belongs to one of them. 

British Prime Minister Margaret Thatcher

In this 1980 file photo, British Prime Minister Margaret Thatcher poses for a photograph in London. During campaigning both Sunak and Truss have claimed to be former Prime Minister Margaret Thatcher’s heir, but Gardiner said that title only belongs to one of them.  (AP)

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"Liz Truss is definitely a Thatcherite. She is a huge admirer of Margaret Thatcher and her policy ideas are heavily influenced by Thatcherism. In contrast, Rishi Sunak is no heir to Margaret Thatcher." 

Gardiner, who was an adviser to Lady Thatcher, told Fox News Digital that: "A lot of his policies are the antithesis of Thatcherite ideas. Sunak’s record as Chancellor where he significantly raised taxes, spent a huge amount of government money, Margaret Thatcher would have been appalled. Sunak is no Thatcher, Liz Truss can make a strong case for being a politician walking in Margaret Thatcher’s footsteps." 

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According to Gardiner, it is looking increasingly likely that Truss will be victorious when the results are announced in early September, but he said if Sunak were to make a comeback, he would have to "reverse some of his policy positions and significantly shift rightwards in his campaign, but I don’t think that Conservative voters would be convinced by him shifting his positions, and I think, right now, Liz Truss is in a dominant political trajectory and is highly likely to be the next Prime Minister."

The deadline for all Conservative Party members to vote is Sept. 2, with the results expected to be released three days later. The winner will replace Boris Johnson as Britain's new prime minister. Elections are not due until 2025, and recent polls show the Left-leaning Labor Party as leading by six points.