1. For those who don't know the difference: A republic is a state with an elected leader, mostly called a president. It is not necessarily a democracy.
2. Democracy means the rule of the common people - and no, the US are an oligarchy (rule of the few), ruled by the few with money and/or media influence. So are most other so-called "Western Democracies" today.
The input of the people is restricted to voting every so often, after that they can only protest in the streets, and we all know how much impact that has.