The Northeast opposed the declaration of war against the British, both because they felt vulnerable to British attack and because, as a shipping region, they felt a war would destroy the Northeast economy. Though Southern and Western representatives voted for the war, it was the people of the Eastern Seaboard that would bear the risk of British attack, and Northeasterners bitterly resented this fact. The differences over the War were glimpses of a growing sectionalism within the expanding US, a sectionalism that would continue throughout the first half of the 19th century and eventually explode in the Civil War. More immediately, as we shall see, the Northeastern dislike for the war would eventually be a major disaster for the already dissipating Federalists.
Why did the US declare war on Britain, and not France? After all, the British fleet would have protected the US from an actual French attack. For one, the War Hawks could not forgive the British for financing Tecumseh. Also, the War Hawks lusted after Canada, which they believed was poorly defended. Finally, a shared Revolutionary history bound the US and France together: without France, the US would likely not have been an independent nation at all. Similarly, the animosity created by the Revolution directed US enmity toward Britain, and vice versa.
In a historical twist dependent on distance and the slowness of communication (a situation that would come to play again at the close of the war, with the post Treaty of Ghent Battle of New Orleans), if the US had delayed its declaration of war, it would have learned that the embargo and the Non-Intercourse Act had worked, and that the Orders in Council had actually been repealed weeks before the June 18, 1812 war declaration.