A lot of people are likely going to try to understand why someone would say such a thing so I thought I'd explain the theory of The Magical Negro minus the politically correct knee jerk reaction many have at the phrase. First and foremost you have to look at Rush himself, he's a relic of another generation. His experiences are not ours. He lived and socialized in era where things and people were distinct from how we do things today. Take for example this image:

https://i.imgur.com/M0Ly6QW.jpg

In Rush's era these sights were common. Black and white movies often had family scenes and ordinary, calmer toned narratives. There were no explosion scenes, no special effects, no talks at the club, no violent themes like ripping up the villain or throwing them off the cliff in a burning car. Back in those days movies were very ordinary, focusing on emotional themes as most old world cinema did at the time. Back in those days the sight of housekeepers in the background was considered a staple of family life. They didn't have need or want babysitters, back then they had caretakers and midwives who did the chore we now attribute to babysitters and daycare providers. Their presence was very expected in virtually any environment, so much so in fact, that these people were considered a common sight in the household. Seeing them so often resulted in a diminished importance on their presence, they became invisible. In old school theater such practices were used openly, often depicting a stereotypical colored worker similar to how democrats today say that we'd have to clean our own bathrooms if we got rid of illegals.

Back in the day it was common for theater plays to cast entire platoons of people on a stage to provide a realistic setting. It became a common occurrence over time for background characters to be the ones to trigger an event in a play. At the bottom of the stratification of characters were side characters with no names who would utter "cues" for characters to do or say something. A background character might shout "what that over there!" or "it's time to leave for work" despite not being involved in the plot in any reasonable way. It became so commonly used that eventually the term "magic negro" became symbolic of any unimportant person being provided with an important role in progressing the entire stage. In modern terms the magic negro was the cue call that provided plot progression for the scene to accelerate forward from a stagnated or fixed theme.

We end that history there, now for Rush's comment about Barack Obama being THE magic negro. Basically the magic negro was a term for an indispensable nobody, an invisible plot device meant to never be seen by anyone except the cast. Enter Barack Obama. Rush made the astute and wise observation that Barack Obama was as he said THE Magic Negro. Barack's role was to rise from out of nowhere and provide important progress despite being by all reasonable expectations, unable to do so in any reasonable way. When the 2008 election came around the nation psychologically EXPECTED Barack to be a magic negro, meaning they thought because he said he would bring change that he actually would. No one actually trusted him to deliver on that promise. In fact no one even knew what that promise meant, "change we can believe in" was designed to never be inclusive to actual change, rather using the slogan as a kind of heroic call for redesign in some way that people never were meant to understand. Rush brilliantly revived the phrase and saw through Hussein, knowing that he was all talk and no substance. "It was his time" has been the call to arms for Democrats and Republicans for several decades now, as you saw with Hillary as well. You can definitely expect this type of rhetoric come 2023 for the Republican party.

In summary, the audience (the nation in this case) expects this guy who came out of nowhere to magically fix all their problems, it's such a strange state of being, pushing a man with no past, no accomplishments, no tales of heroics, magically rises from the darkness straight to the chair of the most powerful person on the planet. What Rush claimed by calling him THE magic negro was that the nation believed him to be the savior, the hero who would pull them out of their dire situation. By believing it was "his time" people thought they would usher in a new era, a new spring in the middle of the harsh winter. They were clearly wrong, very wrong. He did not deliver on that change and made things far worse than they already were. The events unfolding today partially have to do with the deception of being promised with a new era and getting handed a lump of coal instead. The meaning behind Barack THE Magic Negro is that he, being a nobody, was somehow responsible for saving the nation and people believed it simply because there was an expectation that "it was time". The term can be liberally applied to virtually any Manchurian candidate, but does not apply to Joe Biden because he's always been in the spotlight, otherwise he'd fall into the category as well. Sadly you won't find this explained anywhere because it has been scrubbed and edited out of existence on virtually any place you'd expect to find such information. The term has a much deeper meaning than you'd expect, it can be used to explain all kinds of social situations in which we expect an event to unfold with no reasonable logic behind how it's even possible. For example, Mike Pence was the magic negro we expected to come in at the very, very last moment to put a stop to the fraudulent confirmation of votes. Despite it being unlikely to occur, it would have been the most natural occurrence of events, it would have made the most sense for this event to occur than for it not to have. The principle of the Magical Negro is intuition and expectations, or in our case a lack thereof.

Calling someone "A" magic negro implies they serve as a catalyst for change, calling someone "THE" magic negro implies all burden has been placed on their shoulders alone, meaning they are the sole being in this act tasked with being different.