LOL!! I really wish some of you northern supporters would bother looking into your own history before you make statements like that. It is not only provided by the Constitution under the 10th but at the same time was considered as a viable solution on more than one occasion by not only northern politicians but Presidents as well
"The powers not delegated to the United States by the Constitution, nor prohibited by it to the states, are reserved to the States respectively, or to the people."
Now, I don't know what you might mean by the term "secession," but I know what the southern politicians trying to protect slavery meant. They intended to divest the government of the United States of its powers in the southern states. They meant to mess with the powers that are delegated to the United States.
At the time, the southern politicians involved in all of this were desperate. They genuinely believed that the preservation of slavery was vital to the preservation of the southern culture. So they took a gamble. And they lost. And now we know that the preservation of slavery was not vital to the preservation of southern culture. The southern politicians were just wrong about that, too.
In fact, slavery and "secession" now has very few fans anywhere in this country. It's a dead issue.
So, Lincoln can be credited both for keeping us together as a nation and for proving that slavery was not a necessary part of southern culture. And now, we're all together as part of one Union and all but a tiny few of Americans like it that way.