Winthrop,—in denouncing the Compromise measures of 1850, and especially the Fugitive Slave Act, the immediate and complete repeal of which he had advocated.
He stoutly insisted in 1854 that the Nebraska bill should be opposed, not so much as a breach of compact, but rather as the rejection of the Free Soil principle that slavery should be excluded from the Territories by national prohibition.
Letter to Sumner, March 17, 1854. He took part in the Free Soil national conventions of 1848 and 1852, and the Republican convention of 1856; and when elected to Congress in 1858, he was understood to hold the most advanced constitutional positions against slavery.
He held such positions during the first session of his term; and when he was leaving Boston for Washington in December, 1860, he signified to his friends that he should still maintain them against the expected pressure for compromise.
The key to his new departure is most likely to be found in his personal and political intimacy,