You can try to guess what he's going for with the all-lowercase letters — a hip, youthful disregard for stuffy capitalization rules? A fresh approach to governing the country, as well as continental-US-dot-on-the-i patriotism? National unity for everyone except Alaska and Hawaii? But no matter what you think, something is off here.
Look long enough, and you'll see it: m arc o ru bio.
What we have here is a kerning problem.
Design is what makes you like/dislike something without realizing it. The hardest part of a design to get right is the small stuff—the final 10%. The stuff that most rational (normal) people don’t get hung up on. I’m of a mind that a bad presidential campaign logo/typeface won’t really matter much in the big scheme of things, but that a good one can give you a boost. Marco Rubio? He will not be getting a boost. (Also—why is he going to be president for a century? And why is he going to annex Hawaii and Alaska? And aren’t we already fifteen years into the new cent—oh, forget it.) Oh, and for what it’s worth, Hillary will not be getting a boost either.