A long-running dispute over the war's origin is to what extent states' rights triggered it. The consensus among historians is that the war was not fought about states' rights. But the issue is frequently referenced in popular accounts and has much traction among Southerners. Southerners advocating secession argued that just as each state had decided to join the Union, a state had the right to secede—leave—at any time. Northerners (including pro-slavery President Buchanan) rejected that notion as opposed to the will of the Founding Fathers, who said they were setting up a Perpetual Union.