I am not a Democrat in part because they do stupid stuff like this. Jerusalem has always been recognized by the US government and all other UN members except Israel as occupied territory. The UN Security Council of which the US is one of the five permanent members with veto power passed resolution 478 on 20 Aug 1980 declaring for the second time that year that the annexation was illegal. This resolution not only declared the annexation of Jerusalem by Israel "null and void", but also called upon all foreign nations to withdraw any diplomatic missions established in the city. Establishing an embassy in Jerusalem would be a violation of international law and a radical change of long standing US policy.
hat tip: Marc b. at Mondoweiss