According to Ilzetzki, a major priority for the next prime minister should be to clarify "once and for all, the UK's relationship with its larger trading partner," the European Union.

Truss, who voted to remain in the EU in 2016, has since become a staunch advocate for Brexit. She is pushing to rip up the Northern Ireland protocol — a piece of legislation central to the EU withdrawal agreement the UK signed in 2020 — which enables the free flow of goods between Northern Ireland and the Republic of Ireland.

The protocol keeps Northern Ireland subject to EU rules on internal trade, and means that goods traveling between the country and the rest of the UK must be checked.

Critics argue that the arrangement effectively creates a sea border within the UK, and involves burdensome costs and paperwork for businesses.

Truss, while serving as the UK's foreign minister earlier this year, put forward legislation that promised to "end the untenable situation where people in Northern Ireland are treated differently to the rest of the United Kingdom," and protect the country's "territorial integrity."

According to Ilzetzki, a major priority for the next prime minister should be to clarify "once and for all, the UK's relationship with its larger trading partner," the European Union.

Truss, who voted to remain in the EU in 2016, has since become a staunch advocate for Brexit. She is pushing to rip up the Northern Ireland protocol — a piece of legislation central to the EU withdrawal agreement the UK signed in 2020 — which enables the free flow of goods between Northern Ireland and the Republic of Ireland.

The protocol keeps Northern Ireland subject to EU rules on internal trade, and means that goods traveling between the country and the rest of the UK must be checked.

Critics argue that the arrangement effectively creates a sea border within the UK, and involves burdensome costs and paperwork for businesses.

Truss, while serving as the UK's foreign minister earlier this year, put forward legislation that promised to "end the untenable situation where people in Northern Ireland are treated differently to the rest of the United Kingdom," and protect the country's "territorial integrity."