There is something that is confusing to many people today that needs to be explained. The Federalists were the first major political party in the United States, but in 1799, Thomas Jefferson and James Madison formed the second major political Party. The official name of this party was the Democratic Republican Party, but contemporary newspapers often shortened this down to just the Republican party. They elected three presidents: Jefferson, Madison and Monroe. By 1824, there were many fissures in this party. In 1828, when Andrew Jackson assumed the leadership of the Party, he stopped calling in the Republican party and started to call it the Democratic party. In 1830, this dissatisfied members of the Democratic Party formed a new party, which had an official name The National Republican Party, but was usually just called the Anti-Jacksonian party. In 1833 and 1834, Henry Clay reorganized this faction into the Whig Party. The word Republican wasn't used again, until 1852, when the current GOP was formed. Source: "Henry Clay: The Essential American" by David Heidler and Jeanne Heidler

I think you're mistaken. The GOP was founded as the merger of the old Free Soil Party and the remnants of the northern portion of the Whig Party. Before 1850, both major parties attempted to split the difference on the slavery question, as both had northern and southern wings. The Mexican War blew this system apart, as the new western territories made that calculated ambiguity impossible. Both the Whigs and Democrats self-destructed over the next ten years. By 1854, the Whigs had vanished, with its northern antislavery wing becoming the GOP. (The Democrats would split in 1860.)