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.
Edwin Hurlbut
In abolitionist, Liberty, and Free Soil circles the name 'republican' had been bandied around for a number of years, with even Horace Greeley using the term as early as 1852, and is credited to christening the name republican in 1854. In addition, Israel Washburn, U.S. congressman from Maine, used the name Republican in reference to forming an anti-slavery party, there were private meetings in Crawfordsville, Iowa, Ripon, Wisconsin, Exeter, New Hampshire, and the convention in Jackson, Michigan, which all claim to have first named the party republican in 1854. Research completed by Mrs. Page Johnson in 1976, agrees with the column by R.F. Howard in 1903, that Edwin Hurlbut named the Republican Party in Madison, WI., July 13, 1854. Included in Mrs. Johnson's article is a photo of the Republican float in the bi-centennial parade in Oconomowoc in 1976, on which is displayed a replica of the handbill which Hurlbut distributed in June 1854, and added signage, "Hurlbut Named Party Republican".