He made the transition to diplomatic work thanks to his personal connection with former president George Bush. When Bush became vice-president after Ronald Reagan's electoral victory in 1980, Lilley was named as director of the Taipei office of the American Institute in Taiwan, making him the top US representative in the ROC.
之後由於與老布希總統的私人情誼，一九八○年雷根與布希搭檔在選戰中獲勝後，李潔明轉任外交界，出任美國在台協會台北辦事處處長，站上美、中、台交鋒的第一線。