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) Donald Trump's campaign fired one of its senior advisers on Monday, multiples sources confirmed to CNN. Ed Brookover, who helped manage the campaign's delegate operations in the lead up to the Republican National Convention, was fired a little more than six weeks after he was promoted as the campaign's liaison to the Republican National Committee. The firing comes even as the campaign continues to hire more staff in an effort to build up its political operation less than 100 days before the general election. "The campaign has parted ways with Ed, but we are thankful to him for his many contributions and appreciate his continued support," the campaign said in a statement.One senior campaign source says Brookover and Manafort "never saw eye-to-eye" 
 Question:One source said _ has not been involved in high-level meetings for weeks, and another said Brookover was axed from the campaign's list of surrogates about three weeks ago.

Ed Brookover