Like SilverPhantom has mentioned, for New England to lose the war, you'd definitely have to butterfly the UK and Virginia out somehow.
Maybe it would be possible for the Union to get itself some allies? I mean after all, many Russian ships docked on both coasts of the USA.
Of course the Russians had enough trouble with the Ottomans already, but maybe they could somehow be willing to become an ally of the Americans.
And... i believe Prussia did have good relations with the US?
Now, only France was pretty Pro-British during the Confederate War of Independence. Maybe they could be butterflied away too somehow?
-Korporal Nooij,