Ding! Ding! Ding! We have a winner! Why do you think that Lincoln refused all attempts to negotiate?
From the moment he was elected, Lincoln played tough guy, reminding everyone who was within earshot that he had absolutely no intention of compromising his rock-hard principles or entering into, or even taking notice of, agreements (such as, e.g., Buchanan's armistice) that would tie his hands as the employer of the Executive power.
And Unionist historians, distinguishing him from the real Black Republicans, keep telling us he was the "moderate" candidate!
At least he varied his patter a little; later on he turned in "we will not compromise" for "you are too late."
Because there was nothing to negotiate. Lincoln had the choice to accept the southern ultimatum or not. He chose not to.