Origins of the American Civil War
In almost every northern state, organizers attempted to have a Republican Party or an anti-Nebraska fusion movement on ballots in 1854. In areas where the radical Republicans controlled the new organization, the comprehensive radical program became the party policy. Just as they helped organize the Republican Party in the summer of 1854, the radicals played an important role in the national organization of the party in 1856. Republican conventions in New York, Massachusetts, and Illinois adopted radical platforms. These radical platforms in such states as Wisconsin, Michigan, Maine, and Vermont usually called for the divorce of the government from slavery, the repeal of the Fugitive Slave Laws, and no more slave states, as did platforms in Pennsylvania, Minnesota, and Massachusetts when radical influence was high.
Republican Party (United States)
In the period 1850-1870, the Republican Party was more opposed to immigration than Democrats, in part because the Republican Party relied on the support of anti-Catholic and anti-immigrant parties, such as the Know-Nothings, at the time. In the decades following the Civil War, the Republican Party grew more supportive of immigration, as it represented manufacturers in the Northeast (who wanted additional labor) whereas the Democratic Party came to be seen as the party of labor (which wanted fewer laborers to compete with). Starting in the 1970s, the parties switched places again, as the Democrats grew more supportive of immigration than Republicans.