From a POD between 1812 to 1836, screw the USA so badly that the USA loses the mexican american war and does not become a great power. NO loss of the Louisiana territory is allowed.
Have the war of 1812 be a much more decisive British victory. From there you pretty much have a blank cheque as to what you want to do to the US.
Didn't the British want to wrap up the war because of Napoleon? A more decisive victory would probably mean longer and more intensive engagement outside of Europe.
I think it would be easier to devise something along the North - South divide. IMHO that offers the best potential for Ameri-Screw. I.e. The Amistad trial turns ugly and triggers an early secession?
But more importantly, a bad loss in the War of 1812 might sow disillusionment with the federal government or the country itself. The "New England Secedes" possibility is way overblown, but the loss could still sow more regional division. Also, if trade with Britain is routinely cut off due to bad relations, the US economy will be worse off, especially in the South.
You could take that where you want.
Didn't the British want to wrap up the war because of Napoleon? A more decisive victory would probably mean longer and more intensive engagement outside of Europe.