Ok  the whig  party  fell out of the favor with many of its members, so many fractured off and formed the republican party to directly compete with the whigs. The whigs lost and disintegrated, the Republicans  then replaced the whigs. However within the 1860 election the whig party was gone   replaced by the Republican's  still a third party at the time. The democrats  the sole major party  along the the Constitutional union and Southern democrat.