The Federalist Party lost support after the War of 1812 due to their opposition to the war and alignment with Great Britain, leading to their decline.
The Federalist Party lost support after the War of 1812 primarily because it had opposed the war and sided with Great Britain. Their opposition to the war, coupled with the embarrassment of the Hartford Convention's proposals and lack of public trust, led to their decline. Meanwhile, the Democratic-Republican Party's victory further marginalized the Federalists in national politics.
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