EMINEM All Biz Introducing Obama in Detroit … Barack Starts Rapping!!!😲

Eminem kept it all business opening up for Barack Obama at a Kamala Harris event in Michigan … but Barack Obama was so loose, he started rapping a famous Em song.

Slim Shady just introduced Obama at Tuesday’s Harris campaign rally in Detroit, and he kept it pretty brief and played things straight … but when Barry O came out, he lost himself in the music.

Ya gotta see the video … Obama takes the baton from Eminem and start’s rapping Em’s “Lose Yourself” at the podium … and the crowd goes crazy.

After Obama paid homage to the Detroit icon by showing off his rap skills, he started taking shots at Donald Trump … taking a dig at the crowd sizes of Harris’ opponent, and bashing DT for selling merch on the campaign trail.

Barack kept flaming Trump … comparing him to someone’s senile grandpa and telling folks it’s time to turn the page on Trump for good.

Eminem’s used to being the headliner … but he’s content to play opener for Obama here … and it will be interesting to see if the duo helps deliver Harris a key state in the race for the White House.