The Democratic Party that were slave masters before the Civil WarNot completely true. There WERE some Whig slaveowners. What were Whigs? They were 19th Century versions of Moderate Republicans, ie, GOP-e.
Exactly right. The Republican Party was founded as an abolitionist party and alternative to the Whigs in 1854. The Whigs were dissolved in 1860. The party was ultimately destroyed by the question of whether to allow the expansion of slavery to the territories. There were deep divisions in the party on the expansion of slavery question. The anti-slavery faction prevented the nomination of its own incumbent, President Fillmore, in the 1852 presidential election. Instead, the party nominated General Winfield Scott.
Most Whig party leaders eventually quit politics (as Abraham Lincoln did temporarily) or changed parties. The northern voter base mostly joined the new Republican Party. By the 1856 presidential election. By 1860, the party was virtually defunct. In the South, the party vanished.