The phrase describes a specific event: the withdrawal of a nomination by the then-President for a particular individual to a leadership role within the Department of the Air Force. This constitutes the abandonment of a pre-selected candidate for a high-ranking position.
Such actions are notable because appointments to senior government positions typically undergo significant vetting and public scrutiny. The cancellation of a nominee often generates speculation about the reasons behind the decision, impacting public perception of the administration and potentially affecting relationships with the Senate, which holds confirmation power.