Who is stated his belief that the government could not endure half slave and half free in a campaign speech in 1858?

In his campaign speech in 1858, Abraham Lincoln expressed his belief that the government could not endure "half slave and half free." This statement highlighted the moral and political tensions surrounding slavery in the United States at the time, suggesting that the nation needed to resolve the issue of slavery to ensure its survival. Lincoln's assertion underscored his commitment to the principles of freedom and equality, which would later become central to his presidency and the Civil War.