Mexican War

I know I have been doing allot of blogs about Lincoln's possible thoughts on other historical conflicts... but what can i say. I'm a History major. Alright next thought. The Mexican War; arguably one of, if not the most difficult war to defend. Basically, The United States saw land in Mexico, and they took it. There you go! Hard to support huh? Now we know that Lincoln was not in support of the war but was he not in support because if they U.S. won, that would mean that more slave states would be added to the Union, or was he opposed to it on other moral grounds?