The Obama Administration has consistently said that it supports Palestinian statehood, however standing in the way of Palestine's petition to the UN shows that the US is clearly biased in the negotiation process between Israel and Palestine.
Our goal is a two state solution. Obviously negotiations are getting us no where, and it is the most rational course of action for Palestine to pursue UN recognition just like Israel did back in 1948.
Bottom line, supporting the Palestinian statehood in the UN is morally right and helps our diplomatic position.