Before answering your main question, I want to point out that if you look closely at your definitions, the US has never been a true democracy. However, it certainly has been closer to a democracy in the past than it is today. Citizens in the US today don't vote on issues anymore, they mainly vote based on how it will affect their pocketbook. Most of the politicians don't really care about the issues either. They'll only take a stand on issues if their opponent absolutely forces them too. Elections today are really won by being charismatic. Candidates simply have to keep themselves in the public eye, encourage voters in their party to vote, and avoid alientating as many voters as possible. The decision isn't usually made by swaying the other side, but rather by making sure more of your party shows up to the polls.