mexico city mexico government tuesday unexpectedly change two top officials responsible u.s. relations cite concern increasingly anti-mexican climate across border carlos sada previously consul los angeles name ambassador unite state paulo carreno one president enrique pena nieto communications chiefs appoint deputy foreign minister north america new ambassador must still approve senate warn citizens begin feel hostile climate foreign minister claudia ruiz massieu tell local radio announcement anti-mexican rhetoric make clear act different way tendency generate damage bilateral relationship add mexican government officials express concern rise republican presidential front-runner donald trump due repeat verbal attack mexico insistence mexico make pay border wall trump tuesday threaten block remittances undocumented mexican migrants elect president unless country pay billions plan wall trump also call ford announcement would build cars mexico absolute disgrace mexico replace top u.s. diplomats cite hostile climate