Why did Lincoln not talk about slavery in the existing slave states?

Lincoln avoided discussing slavery in the existing slave states primarily to maintain support from border states loyal to the Union, where slavery was still legal. He believed that focusing on preserving the Union was more critical than addressing the issue of slavery directly in those regions. Additionally, he aimed to prevent alienating Northern Democrats and other factions that might oppose outright emancipation. By framing the Civil War as a fight for the Union rather than a war against slavery, he sought to unify the country.