By Nora Redmond Former Manchester mayor Andy Burnham is the presumptive replacement U.K. Prime Minister Keir Starmer resigned on Monday. Prime Minister Keir Starmer has resigned - and analysts say the move increases the chance, though hardly guarantees, that the world's sixth largest economy could see a debt crisis. On Monday morning, Starmer announced he was resigning from his position as leader of the U.K.'s Labour Party after rival Andy Burnham won a parliamentary by-election last week.