Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: (CNN) President Donald Trump was fuming as he sat in his Phoenix hotel watching news coverage ahead of his rally. The venue for his first rally in nearly three weeks looked empty. That's when George Gigicos, Trump's longtime advance man, got a call from Keith Schiller, the director of Oval Office operations who is almost always at Trump's side, asking Gigicos why the crowds were scarce. Gigicos explained that while TV correspondents were live early from the venue, the rally wouldn't start for several more hours and crowds had just begun to trickle in. Soon after, Gigicos heard from Trump himself. The President was irate, warning his former director of White House advance who had since returned to his private contracting business, that the venue better be full by the time he arrived, two sources familiar with the discussions told CNN as they described the scene and the President's reaction.The calls were nothing unusual for any of the advance officials"George will be back," one source familiar with the matter said 
 Question:Gigicos was one of a handful of aides who helmed the _ campaign in its early stage and was the organizing force behind the hundreds of rallies Trump held throughout his campaign.

Donald Trump