Tell the whole story @Wulfie..
Slavery and the emergence of the bipartisan system
From 1828 to 1856 the Democrats won all but two presidential elections (1840 and 1848). During the 1840s and ’50s, however, the Democratic Party, as it officially named itself in 1844, suffered serious internal strains over the issue of extending slavery to the Western territories. Southern Democrats, led by Jefferson Davis, wanted to allow slavery in all the territories, while Northern Democrats, led by Stephen A. Douglas, proposed that each territory should decide the question for itself through referendum. The issue split the Democrats at their 1860 presidential convention, where Southern Democrats nominated John C. Breckinridge and Northern Democrats nominated Douglas. The 1860 election also included John Bell, the nominee of the Constitutional Union Party, and Abraham Lincoln, the candidate of the newly established (1854) antislavery Republican Party (which was unrelated to Jefferson’s Republican Party of decades earlier). With the Democrats hopelessly split, Lincoln was elected president with only about 40 percent of the national vote; in contrast, Douglas and Breckinridge won 29 percent and 18 percent of the vote, respectively.
The election of 1860 is regarded by most political observers as the first of the country’s three “critical” elections—contests that produced sharp yet enduring changes in party loyalties across the country. (Some scholars also identify the 1824 election as a critical election.) It established the Democratic and Republican parties as the major parties in what was ostensibly a two-party system. In federal elections from the 1870s to the 1890s, the parties were in rough balance—except in the South, where the Democrats dominated because most whites blamed the Republican Party for both the American Civil War (1861–65) and the Reconstruction (1865–77) that followed; the two parties controlled Congress for almost equal periods through the rest of the 19th century, though the Democratic Party held the presidency only during the two terms of Grover Cleveland (1885–89 and 1893–97). Repressive legislation and physical intimidation designed to prevent newly enfranchised African Americans from voting—despite passage of the Fifteenth Amendment—ensured that the South would remain staunchly Democratic for nearly a century (see black code). During Cleveland’s second term, however, the United States sank into an economic depression. The party at this time was basically conservative and agrarian-oriented, opposing the interests of big business (especially protective tariffs) and favouring cheap-money policies, which were aimed at maintaining low interest rates.