When the trade dies off so does that economy, and thus a second major reason as to why the South hated tariffs so much. For all practical purposes the Morrill tariff would gut them not once but twice. It gutted them by way of prices since, as exporters, they were the least able of any sector of the economy when it comes to passing on the higher prices to others. It also gutted them by way of undermining international trade, upon which their economy was directly dependent.
Trade and tariff wars had existed for centuries, and had been a major reason for the ongoing wars between France and Great Britain. Ultimately, wisdom prevailed on the European continent, and all barriers to free trade had been eliminated.
Against the backdrop of the obvious advantages of free trade to the overall economy, the Republicans persisted in their efforts to pass the Morrill Tariff. Southern politicians knew how determined the Republicans were in their efforts to establish protectionist measures and they made every effort to resist until it became apparent that the election of 1860 was going to result in sufficient Congressional reapportionment to permit their defeat.
The south had the votes to defeat he Morrill tariff.