Massachusetts Republican Party
The Massachusetts Republican Party was founded in 1854. Drawing together abolitionist and nativist anti-Catholic elements, it quickly became the dominant political force in the state and a powerful arm of the national Republican Party. Significant founding figures include Senator Charles Sumner, formerly of the Free Soil Party, and Speaker of the House Nathaniel Prentiss Banks, formerly of the American Party. 
At the time of the Republican Party's founding in 1854, all of Massachusetts's congressional representatives but Sumner were members of the nativist Know-Nothing Party. However, Banks's role as chairman of the 1856 Republican National Convention, his active support for the Republican presidential nominee John C. Frémont in 1856 and his focus on anti-slavery legislation as Speaker put him at odds with his party. Following the Democratic victory in the 1856 elections and the Dred Scott case in 1857, the national American Party organization collapsed, and most Northern members joined the nascent Republicans. In 1857, Banks ran as a Republican against incumbent Know-Nothing Governor Henry J. Gardner and won a decisive victory.
The Cleveland Leader
The "Leader" was explicitly political from its founding. Cowles' March 5, 1890 "New York Times" obituary claims, "In the Winder of 1854-5 the germ of the Republican Party (United States) was formed in the "Leader" editorial rooms as a meeting was held there which resulted in the first Republican Convention, which was held at Pittsburg. Col. R. C. Parsons, Joseph Medill, John C. Vaughn, Judge R. P. Spaulding, and J. F. Keeler, were at the meeting, which resulted in the consolidation of the Know-Nothing, Whig Party (United States), and Free Soil Parties into the Republican Party."