That was a different fight politically and was the amendment which overturned the 1857 Dred Scott decision which stated that slaves and Free blacks did not have civil rights. Johnson was a far weaker President than Lincoln, the Hero of the War in the North, would have been. Johnson held many of Lincolns ideals on reconstruction but in some ways as the Unionist Govenor of Tennessee had been more radical than Lincoln. Yet Johnson was under fire for being too "southern" in his sympathies?
The fact that it took 2 years to pass the 14th Amendment tells us something about the opposition to this measure even with a northern controled Congress and White House.