Weed had always disliked slavery and favored its containment; he discounted southern threats of secession and saw only advantages in attacking northern compromise Democrats as prosouthern and proslavery. Thus he disliked the Compromise of 1850 and welcomed the revival of sectional issues with the Kansas-Nebraska Act of 1854. Although eager to see antislavery Democrats and Whigs united in the new Republican party, Weed blocked its full organization in New York until Seward had been safely reelected. To reduce the new party's apparent ties to the Whigs, Weed gave up the editorship of the Evening Journal from 1855 to 1858, although he remained active behind the scenes. He discouraged Seward from seeking the Republican presidential nomination in 1856, fearing a loss. While Seward generally respected Weed's advice as astute and well meant, others were less understanding. Greeley, convinced that Weed was unfairly squelching his own ambitions for office, broke with both Seward and Weed. Former Democrats among the Republicans felt Weed favored former Whigs over them. Dissension among New York Republicans was one factor that cost Seward the presidential nomination in 1860, despite Weed's best efforts in his behalf.
Field, Phyllis F., "Weed, Thurlow," American National Biography Online, February 2000, http://www.anb.org/articles/04/04-01194.html.