Sentence:  <WSD>Sherpas</WSD> from the European Union and 19 countries worked through the week to salvage a meaningful joint statement, culminating in an all-night session on Friday. 
Meaning of the word marked with <WSD> tags:  A high-ranking government official who works tirelessly in the background to conclude the text of an official communiqué, typically from a G7 or G20 summit.