Your challenge, should you accept it, is to make Andrew Jackson declare himself King of America.
Well, I can't say that many Americans, Northerners in particular(New England Yankees above all!), would take too kindly to old Hickory pulling such a movie. Southerners, on the other hand, might not be so against it; in fact, if Jackson can convince the planters that he'd protect their privileges, then I'd imagine he'd have their support wrapped up real tight. However, though, it definitely seems highly likely that the North, at least most, if not all of it, would secede rather shortly, either in the name of the old U.S., or something else.
I think the only really major short-term problem for the new Kingdom of America after this, if the North decided not to invade, that is, would be what to do with Texas once it breaks off of Mexico: annex it, and possibly be able to reach the Pacific, or just be content with allying with the Texians?
Regardless, I can see a scenario like a mix between DoD and Lost The Game's FSA mini-TL from the "Alternate Presidents" thread(but maybe not with *Communism) developing: a slaveowner-dominated authoritarian South vs. a rapidly industrializing, and democratic, if perhaps not perfectly so, North.