The Republican politician is a HUGE football fan -- and with the Jacksonville Jaguars losing their starting QB, Nick Foles, to a shoulder injury, some people think the Jags should kick the tires on Kaepernick.

Rubio is one of those people ... telling us straight-up, "Certainly there aren't 64 better QBs playing in the NFL right now."

Marco notes that NFL personnel decisions are based on more than just talent and ability -- but makes it clear he thinks Colin's current unemployment status is about more than what he can do on the field.

"I'm not an NFL owner but I can tell you I don't think there are 64 better quarterbacks ... that's obviously not football that's keeping him away."

Rubio says the shot callers on NFL teams "think he brings many other things with him that they don't want around" ... an obvious reference to the media firestorm over Colin's kneeling protest.

We asked Marco if he would consider Colin if he ran the Jags ... and this is what he told us.

"If I were an owner, and he was the best guy, I'd bring him in despite the other stuff. But, there's a lot that goes into that."

We all know how President Donald Trump feels about Kaepernick ... he's called for the NFL to fire any "son of a bitch" who doesn't stand for the national anthem.