A student walks past a billboard in Newry, Northern Ireland, protesting the U.K.’s departure from the European Union. A majority of voters cast ballots against Brexit in 2016; the region has become a central point of contention in negotiations.

A student walks past a billboard in Newry, Northern Ireland, protesting the U.K.’s departure from the European Union. A majority of voters cast ballots against Brexit in 2016; the region has become a central point of contention in negotiations.