premise: Thomas Jefferson worked with James Madison.
hypothesis: James Madison . Breaking with Hamilton and the Federalist Party in 1791 , he and Thomas Jefferson organized the Democratic-Republican Party . Thomas Jefferson . Jefferson and James Madison organized the Democratic-Republican Party to oppose the Federalist Party during the formation of the First Party System . With Madison , he anonymously wrote the controversial Kentucky and Virginia Resolutions in 1798 -- 1799 , which sought to embolden states ' rights in opposition to the national government by nullifying the Alien and Sedition Acts .