 The party is one of two legally established, statewide political parties in Illinois, the other being the Democratic Party.The Illinois Republican Party was organized at the Bloomington Convention in Major's Hall in Bloomington on May 29, 1856.Its founding members came from the former Whig Party in Illinois after its members joined with several powerful local political factions including, notably, the Independent Democrat movement of Chicago that helped elect James Hutchinson Woodworth Mayor in 1848.