My ideal "coolest" model is one kinda like the UK
A unitary state, but with devolved powers to certain regions (most likely the Deep South, New England, and California). The President is directly elected by a plurality of the vote, and two main executive parties exist. The legislature is Unicameral and has 4-5 main parties as it is (in ATL 2017) an MMP system allowing for PR.
Congress is much more powerful, able to vote out cabinet members and such.
That’d be fascinating, but I feel like the devolved powers would historically go to much different places.
Hell, with a Constitution set up like that, I doubt California would exist as it is in its current form.
New England is a good early contender, as they would probably be very mad that they were not given equal representation as states. Perhaps South Carolina would demand the same treatment under Andrew Jackson (when they threatened secession IOTL) and then the Civil War be averted with most of the South just doing the same (they probably wouldn’t just join South Carolina as a devolved entity because many states in the Confederacy wished to go their own ways after the Civil War and if that’s an upfront option, would have).
Maybe instead of a President a collective executive like the Federal Council in the 1848 Swiss Constitution? The 1776 Pennsylvania constitution had this but it proved unworkable as the councilors were elected one for each county and as the number of counties rapidly increased after 1776 it became too unwieldy. The remedy is to use the Swiss solution: limit the number to a small number like 7 (more than enough for the number of heads of department needed, at least by the needs at the time the constitution is framed) and have them elected by some means from the whole country: either use the electors as with the president or have the lower house of Congress elect them, with the proviso that no two can be from the same state. This avoids giving any single state too much influence.
I love this idea.
How would they be elected? All at the same time?
I was thinking that three could be like members of the UN Security Council, with the three biggest states being guaranteed seats (going by the census, that would be: Pennsylvania, Virginia, and North Carolina at first and then Pennsylvania, Virginia, and New York for decades to come) and the other four being elected every year.
That could end up really keeping whatever the current political order is strong in the federal branch. You wouldn’t have surprises in the Presidency like Theodore Roosevelt or Donald Trump without significant reform.