Rep. Alexandria Ocasio-Cortez is coming out swinging for Abdul El-Sayed ... calling claims linking the Michigan senatorial candidate to the Muslim Brotherhood flat-out racist.

Charlie got AOC on Friday at a Culver's in Michigan, where she's been campaigning for El-Sayed ... and he asked whether the Muslim Brotherhood controversy was rooted in reality or racism.

AOC didn't mince words ... saying the allegations fall "into racist very clearly" and blasting critics for dragging El-Sayed's painful family history into politics.

The controversy stems from old social media posts by El-Sayed's half-sister suggesting their mother was involved with the Muslim Brotherhood decades ago ... but he has denied having ties to the group.

AOC points out El-Sayed's parents split shortly after he was born, and he grew up without his mother ... arguing just about everyone has relatives who've made questionable choices, but that doesn't mean those choices define them.

And AOC isn't budging on her support ... calling El-Sayed "one of the most patriotic people" she's ever met.

Charlie and Jacob have had boots on the ground in Michigan for a few days, and they also caught up with El-Sayed this week in Detroit.

He fired back at attacks involving his Muslim faith ... saying his religious beliefs are exactly why he wants an America where everyone's constitutional rights are protected, no matter who they are, who they love or how they worship.

And on a lighter note ... AOC told us it was her first-ever Culver's visit, where the burgers and cheese curds apparently changed her life. It's not El-Sayed pitching us on Gatorade Zero, but it's close.

Politics aside ... sounds like AOC's officially joined the curd caucus!