Lincoln considered slavery a moral wrong and worked for its abolition. He opposed slavery's
extension with equal fervor, but on this matter his view (like that of most Republicans
[Durden 1965, pp. 364-365]) seemed to be shaped by economic as well as moral concerns.
He wished to protect midwestern farmers and free laborers from southern planter and slave
labor competition.' If slavery crosses its present borders, he said, black workers will be
everywhere, "as every white laborer will have occasion to regret when he is elbowed from his
plow or his anvil by slave niggers" (Lincoln 1953-1955, 3:78).
Read the entire statement in context from Lincoln's speech at Carlinville IL --
http://quod.lib.umich.edu/l/lincoln/lincoln3/1:7.1?rgn=div2;view=fulltext
Certainly Lincoln opposed the extension of slavery. Until reading this I never understood that he also opposed people of color moving into the western lands, slave or free.
On the term "Southern Rights", this meant the rights of a Southerner to take his property into any territory belonging to the United States. Southern Rights Democrats insisted that a territorial legislature could not vote slavery up or down. Until a territory became a state, only Congress had jurisdiction in such matters, they declared. Sometimes the term was rendered States Rights, or the rights of all states to the territories.