the republican party grew out of opposition to the kansas–nebraska act, which was signed into law by president franklin pierce in 1854. the act opened kansas territory and nebraska territory to slavery and future admission as slave states, thus implicitly repealing the prohibition on slavery in territory north of 36° 30′ latitude that had been part of the missouri compromise. this change was viewed by anti-slavery northerners as an aggressive, expansionist maneuver by the slave-owning south. opponents of the act were intensely motivated and began forming a new party. the party began as a coalition of anti-slavery conscience whigs such as zachariah chandler and free soil democrats such as salmon p. chase.