a) The US has a two-party political system because of two structural features in American politics: single-member districts and winner-take-all elections. Both features encourage the existence of 2 major parties, as smaller parties face great difficulty in winning elective office.
b) Being a capitalist country, the left-wing party will not be of much existence in USA
c) They can play a spolier role by taking a few votes and affecting the vote count of bigger parties
