The candidate for Reform U.K., the right-wing party of British lawmaker and ally of President Donald Trump, Nigel Farage, won a parliamentary by-election by six votes, taking the seat from the governing Labour Party in a stunning political upset.

Nigel Farage’s right-wing Reform UK won a fifth parliamentary seat, its first post as mayor and many positions on local councils in early election results on Friday which underscored the threat it poses to Britain’s main two political parties.