I mean, Britain joining could rectify that of course. Certainly no GOP candidate would ever be elected again without an utterly massive swing to the left. England alone (which might I guess end up divided into states by region) is vastly bigger than even California, and about as solidly to the left on social and economic issues; there aren't that many of our Conservatives who oppose things like the NHS and marriage equality. Also we could run Boris for the presidency, which would be hilarious and, as much as I increasingly loathe the man, could still potentially be the best option on the ballot paper.
Not sure whether we'd just join as England, or as some regional collection like Northumbria, Mercia, East Anglia, Wessex, Kent, London, Cornwall (the latter would bring us closer to a collection of US states in population terms; Mercia would be a fairly sizeable state in population terms, Cornwall would be the new baby, being about the same population as Wyoming). Would make a lot of difference to the Senate which one we did.