I believe that at least part of the reason for secession, was that the election of Lincoln had many in the south believe that he was going to pass laws outlawing slavery in all states.
let me finish my coffee first
Their belief was well founded. That's exactly what he did.
Lincoln, nor any other President has the Constitutional power to pass laws. Only the Legislature, i.e. Congress can make laws and back then Federal Laws only applied to things that the Constitution said the Federal Government was responsible for. Either way the Congress would have had to pass a law banning slavery and the southern democrats would never had allowed that to happen. Remember, in those days it took 67 votes in the Senate to overcome a filibuster so as long as one person was able to talk for 24 hours and the legislation could not garner 67 votes to break the filibuster that legislation was dead and could not be taken up again until the next Congress was seated. This was how the dems, during Jim Crow, were able to stop the R’s from passing anti-Jim Crow legislation, its also how the dems stopped the R’s from passing the Voting Rights Act, and the Civil Rights act from the end of reconstruction till the 1960’s.