in congress, banks sat on the committee of military affairs. he bucked the democratic party line by voting against the kansas–nebraska act, which overturned the 1820 missouri compromise, using his parliamentary skills in an effort to keep the bill from coming to a vote. supported by his constituents, he then publicly endorsed the abolitionist cause. his opposition came despite long stated support for manifest destiny (the idea that the united states was destined to rule the north american continent), which the bill's proponents claimed it furthered. in 1854 he formally joined the so called know nothing cause, a secretive populist and anti-immigration nativist movement – officially named american party since 1855. he was renominated for congress by the democrats and free soilers, and won an easy victory in that year's know nothing landslide victory. banks was, along with wilson and governor henry j. gardner, considered one of the political leaders of the know nothing movement, although none of the three supported its extreme anti-immigrant positions of many of its supporters.