Lawmakers began debating legislation that rewrites trade rules for Northern Ireland on Monday, the first step on what could be a rocky journey through Parliament.

If approved by lawmakers, the legislation would remove checks on goods entering Northern Ireland from the rest of the U.K., thereby scrapping parts of a trade treaty that Johnson signed before Britain left the EU in 2020.

The British government says the rules, known as the Northern Ireland Protocol, are burdening businesses and undermining peace in Northern Ireland.

Foreign Secretary Liz Truss replied that the government’s plans are the only solution to resolve trade problems in Northern Ireland because the EU has been unwilling to reopen negotiations.

But Johnson said Monday that questions about his leadership were no longer relevant.

Instead, to protect the EU’s single market, there are checks on some goods, such as meat and eggs, entering Northern Ireland from the rest of the U.K.

“You have got one tradition, one community, that feels that things really aren’t working in a way that they like or understand — you’ve got unnecessary barriers to trade between Great Britain and Northern Ireland,” Johnson said.