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.
Senate Republican Conference
Effective with the start of the 116th Congress, the conference leadership is as follows:The Republican Conference of the United States Senate is a descendant of the early American party caucus that decided party policies, approved appointees, and selected candidates. The meetings were private, and early records of the deliberations do not exist. Senate Republicans began taking formal minutes only in 1911, and they began referring to their organization as the "conference" in 1913. An early outgrowth of the effort to enhance party unity was the creation, in 1874, of a steering committee to prepare a legislative schedule for consideration by the conference. The committee became a permanent part of the Republican organization.