This from the fella that prevented the Secession decision from going before the SCOTUS out of fear it would have been determined constitutional and in the bargain save 600,000 American lives...
(Sorry for the distraction and rant but Lincoln is not my favorite as you can tell. I would prefer the logic of the founders in supporting the constitution. Lincoln was not one to be tightly bound by his oath to support it.)
Lincoln also said in his First Inaugural: "You have no oath registered in heaven to destroy the Government, while I shall have the most solemn one to 'preserve, protect, and defend it."
However, his oath was NOT to 'preserve, protect, and defend' the GOVERNMENT, but was to 'preserve, protect, and defend' the Constitution of the United States of America. He even acknowledged the Constitution's silence upon the legality of states' secession, so he didn't uphold the Constitution in that regard.